I. BACKSTORY
A. HISTORY
The modern German navy was always part of a continental-minded military power. It developed after 1848 in two wars against Denmark from a short-lived German democratic fleet, a Prussian fleet, and a North German Federal precursor. It was eventually established during the 1870–1871 war against France upon the foundation of the German Empire under Emperor Wilhelm I. In this war the weak German naval forces could not effectively contest the French blockade of their North Sea and Baltic ports but did manage to protect the coasts.
Emperor Wilhelm II promoted a strong navy to advance Germany’s overseas and European interests. He found in Alfred Tirpitz an energetic manager to build up his navy. Tirpitz advocated a fleet that would surpass that of the French and threaten the British. His “risk” theory held that a fleet large enough to cripple the Royal Navy in battle could give Germany freedom of action on the seas and keep Britain out of a future continental war.
Tirpitz’s theory failed in practice. The British, who held a 3:2 superiority over the German High Sea Fleet, entered the First World War and proceeded to frustrate German hopes for an early battle near their own ports by maintaining a distant blockade. The emperor had hoped for an agreement with Britain after a quick victory over France, but this did not materialize. The only major confrontation between the British and German battle fleets at Jutland in 1916 was indecisive. The German commerce war against British supply lines in the Atlantic had some effect, but the unrestricted sinking of merchant ships by submarines provoked the United States to enter the war on the side of the Allies in 1917. The ensuing German defeat led to the breakup of the German Empire and the scuttling of the German High Seas Fleet at Scapa Flow in 1919.
The Treaty of Versailles reduced the new German Reichsmarine to a coast defense force of eight pre-dreadnought battleships, eight old cruisers, and minor warships. It limited personnel to 15,000 men, and aircraft and submarines were completely forbidden.
B. MISSION
The wish to avoid a new confrontation with Britain dominated planning in the 1920s and early 1930s. Poland and France were regarded as possible opponents. In the 1932 Geneva disarmament conference, Germany called for equality for all League of Nation members and for the removal of treaty restrictions, but France’s security concerns blocked any compromise. Germany subsequently left the conference and withdrew from the League of Nations the next year. A separate German–British treaty was signed on 18 June 1935 limiting the German fleet to 35 percent of British tonnage along with 45 and later 100 percent of submarine tonnage.
A setback in the Anglo-German accord remained the limitation on submarines. Opinion within the German navy toward submarine warfare was split. Reflecting the tradition of the Imperial Navy, Admiral Erich Raeder, the navy’s commander in chief, considered battleships the center of any fleet, and most of his staff thought the same. They believed that submarines could be neutralized by developments in antisubmarine warfare and would likely play a minor role in any future war. The other school of thought, led by Captain Karl Dönitz, considered the submarine the best weapon for a minor navy such as Germany’s.
A war against France and Russia was held possible in 1936 and submarines were developed accordingly: a 250-ton type for coastal waters, a 500-ton type for the Mediterranean, and a 750-tonner for the ocean. The possible use of aircraft carriers together with cruisers in the Atlantic was discussed, but Hitler discounted the carriers as being vulnerable “gas boxes.” Instead, the navy planned to use armed merchant cruisers, as in World War I. Nonetheless, two 20,000-ton (actually, 23,000-ton) aircraft carriers were laid down to exploit the treaty’s opportunities.
The political climate changed in 1938 with the Czechoslovakian crisis. Although the feared war loomed on the horizon, Hitler still considered a conflict with Britain unlikely before 1944–1945. In the meantime the German navy was to expand considerably. He wished to have Germany’s two newest and largest battleships, Bismarck and Tirpitz, ready in early 1940 and wanted to commission six even larger superbattleships as soon thereafter as possible. The scheme of the so-called Z-Plan emerged. Of the two options discussed—battle cruisers of a smaller type but in a greater number or superbattleships—Hitler and the navy’s leaders chose the latter. In addition to the battleships, the Z-Plan called for three battle cruisers and sixteen light cruisers. All new ships were to have diesel engines or at least mixed propulsion for greater range. Submarines were still regarded as strategically unimportant.
In a strategic concept for a possible war with Britain dated 25 October 1938, the inferior German navy’s main task was the destruction of enemy shipping. This would be impossible to accomplish from only the German North Sea ports and bases in northern Norway or along France’s Atlantic coast were regarded as vital. The naval staff saw battleships as a means for cruiser warfare or at least as a necessary backup to a cruiser force.
A naval study from early 1939 identified the occupation of western Russia as a German war aim and specified an offensive mine barrage in the Gulf of Finland in the war’s beginning to hem in the Soviet navy. A war game conducted about that time underlined the prevailing strategic thoughts—an offensive campaign against British maritime traffic and the protection of Germany’s own Baltic and North Sea traffic with Scandinavia—to guarantee the import of vital iron ore from Sweden. In the Mediterranean, Italy was to maintain ties with North Africa. Naval staff doubted Rome’s ability to weaken the British bastions of Suez and Gibraltar and recommended a German operation to take these positions. Planners regarded a war before 1943 as unsafe but were more optimistic about outcomes after that date with the Z-Plan production coming on line.
II. ORGANIZATION
A. COMMAND STRUCTURE
1. Administration
In 1928 Admiral Raeder became the German navy’s commander in chief. His staff was the Naval High Command—Oberkommando der Kriegsmarine (OKM), and from 1933 he reported directly to Adolf Hitler who became supreme commander of the Armed Forces—in 1938. OKM was on an equal level of command with the army high command (OKH) and the high command of the air force (OKL), with all three coordinated by Oberbefehlshaber der Wehrmacht (OKW).
The naval staff, headed from 1938 by Admiral Otto Schniewind, was called the Seekriegsleitung. Prewar the operations department was led by Rear Admiral Kurt Fricke, who replaced Schniewind as chief of naval staff in June 1941. Eight more departments covered other aspects of naval administration. The navy created Marinegruppenkommando Ost in 1938 to cover operational needs in the Baltic and Marinegruppenkommando West in 1939 for the North Sea and Atlantic. After the occupation of Norway, Marinegruppenkommando Nord became Marinegruppenkommando Nord.
Two territorial commands administered the North Sea coast (Marinestation Nordsee) and the Baltic coast (Marinestation Ostsee). Additional commands were added after the conquest of Norway, France, Greece, and the Ukraine. These included Admiral Norway, France, Black Sea, Aegean, and Adriatic, which reported either to the Marinegruppe Kommando or directly to the Seekriegsleitung. The Fleet Commander, overseeing forces afloat, reported to one of the Marinegruppe Kommandos depending on the fleet’s area of operations. Commander U-boats, reported directly to Seekriegsleitung, as did the small Danube Flotilla.
2. Personnel
In 1935 Germany reintroduced universal conscription and fixed military service at three years. In 1939 before the outbreak of war the Kriegsmarine’s personnel strength was 50,000; conscription raised it to 404,000 in May 1941, and there were approximately 800,000 enlisted men in July 1944.
Draftees entered service as Matrose (deck rating) and were trained to different functions at Kiel, Eckernförde, Stralsund, Sassnitz, Wilhelmshaven, Leer, Wesermünde Brake, and Glückstadt in so-called Schiffstammabteilungen (naval manning depots). Noncommissioned officers were educated in schools at Kiel-Friedrichsort, Wesermünde, and Plön and started their different specialized careers as Maat.
The training for naval line officers lasted three years. The first five months were spent in a Schiffstammabteilung at Stralsund with infantry drill. After four months on a sail training ship they became cadets, and after eight and a half months’ education on training vessels such as Emden, Schlesien, or Schleswig Holstein, they were promoted to Fähnrich zur See (midshipman). After a vacation and seven months at the naval academy at Mürwik, they received five more months of weapon training. In the last six months they trained on board ship and graduated as Leutnant zur See (ensign). Engineer officers, weapon officers, and administration officers underwent similar programs. The Kriegsmarine could draft many reserve officers and men who had prior naval service. Many merchant marine officers also received abbreviated instruction.
The main naval academy was, from 1910, in a massive brick building at Flensburg-Mürwick, but during the war, facilities at Schleswig, Heiligenhafen, Husum, and Heiligendamm were also used.
In addition to numerous shore facilities, the Kriegsmarine maintained school flotillas to train recruits and officers. There were school flotillas for minesweepers and motor torpedo boats but the submarine school flotillas were by far the most numerous. The 21st and 22nd flotillas at Pillau and Gotenhafen, respectively, used the small Type II submarines, whereas the 23rd and 24th flotillas at Danzig and Memel had Type VII boats. The 25th and 26th flotillas at Libau and Pillau were nicknamed the “shooting flotillas” because new boats with their raw crews trained on a fixed schedule, launching sixty to seventy torpedoes per boat under all conditions—surfaced, submerged, in daytime, and at night. After this training, the 27th Flotilla at Gotenhafen provided tactical training in a ten-day “convoy battle” with cargo ships and auxiliaries acting as targets and torpedo recovery boats playing the role of escorts. A lamp replaced the warhead on the training torpedoes so the target ships could observe “hits.” Every submarine had a training officer, and up to two boats within a training course could be “flunked.”
3. Intelligence
The Kriegsmarine’s intelligence service was a department of the Seekriegsleitung called Marinenachrichendienst. The office designated Funkaufkläung (radio intelligence) had separate branches for radio interception and interpretation (B-Dienst) and deciphering radio signals, xB-Dienst. The latter had 1,100 men and women, 949 of them used for deciphering. They were assisted by Hollerith computers.
Although the French and British codes were changed at the beginning of the war, xB-Dienst was soon able to decipher some of the British and all of the French signals. At one point the British changed their codes up to four times a month. The Germans were generally able to break the code after about five days. Depending on the code being broken, the Germans could read up to a quarter of the British radio traffic. They could also read the British and Allied Merchant Ship (BAMS) code, which provided valuable information during the Battle of the Atlantic’s early phases. In February 1942, B-Dienst broke into the code used for communication with many of the Atlantic convoys, but a change of code in March 1943 blinded them. At the end of 1943, after the British began to change their cipher daily, the xB-Dienst was no longer able to penetrate British codes. After the sinking of the Canadian destroyer Athabaskan in April 1944, drifting code documents were recovered that improved the German position, but the war ended before a break could be achieved. Until April 1942 several U.S. Navy codes could be broken. This ceased with newly introduced codes. Russian codes were easier to penetrate. For operations involving the larger vessels, groups of B-Dienst specialists served aboard to provide firsthand information and disrupt enemy signals.
With respect to its own codes, Germany introduced the Schlüssel C coding machine in 1926, followed in 1934 by Schlüssel M, called Enigma. Berlin was very confident that this machine rendered its codes completely secure. The sinking of all supply ships in the Atlantic after the Bismarck operation in the summer of 1941 led the U-boat command to introduce a new code machine, the Enigma M4 in February 1942. The British broke the Luftwaffe code in spring 1940 and the naval code in spring 1941 but were unable to read codes produced by the M4 until the end of 1942.
B. DOCTRINE
1. Surface Warfare
Although, in the aftermath of the First World War, Germany was reduced to the size of a minor navy, tactical training still followed the traditional idea of a fleet encounter between lines of battleships. The heavy guns were to open up in a fast series of rounds, a so-called fork. The first round was only to warm up the guns and was not spotted. The following rounds were shot very quickly with small variations in the actual measured range. At greater ranges three salvos were in the air before the first reached the target area. Most often one of the salvos would straddle, which meant that its shells would splash in front of and beyond the target, and shooting at the identified range would start. To get quicker results, the battery was often split in two and alternated fire. It was also considered easier to spot the fall of shot from four splashes rather than eight.
The traditional idea of torpedo boat attacks at night or from the battle line’s unengaged side predominated before the war. In an effort to improve nocturnal torpedo boat attacks, the Marinenachrichtendienst, or signals service, developed a radar in cooperation with the GEMA Company in 1934. This radar operated on the 50-cm wavelength and could detect vessels up to 10 km away. A pre-war doctrine called for shore-based radar stations to guide torpedo boats to their targets. This concept worked well on the night of 23 October 1943 when a British cruiser and six destroyers tried to intercept a German convoy off the French channel coast. Five radar-directed torpedo boats surprised them and torpedoed and sank the cruiser Charybdis and one destroyer without loss to themselves.
2. Aviation
At the end of the First World War, the Kaiserliche Marine possessed 1,478 planes distributed between thirty-two seaplane stations along the North Sea, English Channel, Baltic, Black Sea, and Mediterranean as well as seventeen airports. The Treaty of Versailles prohibited German air forces. In spite of this, the army and navy trained pilots and developed aircraft. The Reichsmarine used civilian organizations like “Aerosport GmbH” at Warnemünde as a disguised naval air force. In 1925 the navy established a civil aircraft company, Severa, and in 1926 purchased the aircraft factory Caspar–Werke AG at Lübeck-Travemünde, which was later developed as the trial base for seaplanes. From 1933, however, when the NSDAP party took power and Hermann Göring became the minister of air, the still camouflaged Luftwaffe assumed the development of all military aviation, which frustrated the navy because it believed it could do a better job meeting its specific needs than an independent service could. The Luftwaffe established squadrons at Warnemünde, Kiel-Holtenau, and List/Sylt. Shortly after it was officially founded in March 1935, it ordered 153 planes for naval cooperation, and by 1936 there were eight naval reconnaissance, multipurpose, and fighter squadrons.
In 1934 the navy commenced development of a 450-mm aerial torpedo based on a Norwegian type called the F5. Because of a lack of coordination between the Kriegsmarine and Luftwaffe, this torpedo proved unsatisfactory. After some improvements the new LT5a performed better but production, which began at the end of 1940, climbed very slowly. The navy purchased Italian aerial torpedoes called the F5W and F5i. In 1942 a blockade-runner brought seventy Japanese aerial torpedoes to Germany. However, their performance was inferior to the F5W and they were relegated to use on motor torpedo boats (MTBs). From the end of 1941 the Luftwaffe took over the development and production of aerial torpedoes. The resulting weapon, the LTF5b, proved satisfactory. During the war, fifty-eight merchant vessels displacing 333,135 GRT (gross registered tons) were sunk by German aerial torpedoes, and eighteen ships totaling 146,673 GRT were damaged.
3. Antisubmarine
The minor role played by antisubmarine forces during World War I, when German surface ships sank only two submarines (by gunfire), failed to establish an antisubmarine warfare tradition in the German navy. Given the restrictions of the Versailles Treaty, the ban of U-boats, and the concentration on surface warfare, antisubmarine warfare was considered unimportant in the postwar period and was possibly influenced by British propaganda claims for the great efficiency of the Asdic underwater detection system introduced during the 1920s. Moreover, specialization in antisubmarine warfare was unlikely to advance an officer’s career.
During the Kriegsmarine’s peacetime expansion, the requirements of fleet operations occupied the small number of destroyers and torpedo boats, and they were ill equipped for the antisubmarine role. No purpose-built antisubmarine vessels were commissioned before the war. For the 1938 naval training exercise, a temporary Unterseeboots-Jagd (UJ, subchaser) flotilla was formed at Flensburg by modifying fishing vessels. Based on the experiences gained in the exercise, two UJ-flotillas were temporarily established in July–August 1939. Each flotilla consisted of eight modern fishing vessels, each displacing about a thousand tons. The intended return to their private owners was cancelled when war broke out one month later and the Kriegsmarine entered the war with sixteen auxiliary subchasers in commission.
Once war commenced, Germany’s sea-lanes were largely restricted to coastal waters along controlled territory with overseas trade quickly blocked by Allied navies. Standing combat instructions designated Germany’s few capital ships for independent raider operations in distant waters without close antisubmarine escort. Thus, German antisubmarine efforts were initially reduced to escorting warships and coastal convoys close to bases and along the coastline. Contingency plans in the event of war foresaw the conversion of civilian fishing trawlers and whalers into military ships for the antisubmarine role. However, many of these small, slow vessels carried inadequate antisubmarine equipment to prevent attacks. To compensate for the lack of ships and trained personnel, the Kriegsmarine deployed extensive mine barrages along the coastal shipping lanes. Moreover, apart from the mines, shallow water often kept enemy submarines out of these areas.
To meet the demand for personnel, an antisubmarine school, the UAS (U-Boot-Abwehr-Schule), was established at Neustadt on 25 September 1939. In November 1939 it moved to Gotenhafen and finally in July 1943 to Bergen, Norway, with a detachment at Hatvik, Norway. Using captured foreign submarines as target vessels, surface combat units were trained in antisubmarine techniques as far as operational needs allowed.
Throughout the war, German antisubmarine vessels were organized in flotillas of up to ten ships, which were normally allocated to regional navy commands. Initially, the focus was on German waters with 12th UJ-flotilla operating in the North Sea and 17th UJ-flotilla in the Baltic Sea. The 11th UJ-flotilla was formed by eight trawlers at the end of September 1939, and a formation of ten small whalers reinforced the 12th UJ-flotilla in November. Following the occupation of Denmark and Norway and the defeat of France in 1940, the operational area widened greatly. The limited number of antisubmarine vessels was frequently shifted between the various theaters according to need. Changes in the deployment policy for Allied submarines and the start of the German campaign against the Soviet Union in summer 1941 effectively limited the operational areas to the Eastern Baltic Sea, the Norwegian coast, and the Bay of Biscay. In May 1941 a new 14th UJ-flotilla was established, which was eventually based along the French west coast.
To secure the supply lines from Greece to the German garrison on Crete, the 21st UJ-flotilla was formed at Piraeus, Greece, in December 1941, using a variety of locally available ships. In December 1942, following the occupation of Vichy France, Germany established the 22nd UJ-flotilla using converted French fishing trawlers. This flotilla helped escort traffic to North Africa and started operations along the Italian west coast two months later. Similarly, the 1st UJ-flotilla was built up in the Black Sea in May 1943 to escort traffic along the German controlled coasts. This flotilla consisted of former military transport ships of the KT class. Despite the often poor condition of the ships available to these flotillas, they achieved some remarkable results against Allied submarines until the end of 1943.
Following the Italian armistice, captured corvettes of the Gabbiano class were used to strengthen the 22nd UJ-flotilla and create the 2nd UJ-flotilla in the Adriatic. Although these corvettes were well-designed antisubmarine warfare (ASW) ships, the deteriorating German position in the Mediterranean compromised antisubmarine operations during 1944–1945. Only in the Black Sea, where the 1st Flotilla was augmented by the 3rd and 23rd UJ-flotillas formed in April–May 1944 from small wooden-built fishing boats, did success against Soviet submarines continue into 1944. With the loss of the German positions on the Balkan Peninsula in the second half of 1944, German naval operations in the Black Sea and the Aegean Sea ceased and existing flotillas were disbanded.
The navy heavily mined the Gulf of Finland in 1941 to prevent Soviet submarines from entering the central Baltic Sea, which was vital for its supply lanes and training grounds. When the Soviet navy continued its submarine campaign in these waters during 1942 despite suffering severe losses, the navy effectively blocked the western exit of the Gulf of Finland with a net barrier in early 1943. Only after Finland signed an armistice with the Soviet Union in September 1944 did Russian submarines enter the central Baltic. To counter the new threat, the 1st and 3rd UJ-flotillas were re-created at the end of October 1944 using fishing boats and former air force sea rescue motor launches. These vessels, however, proved completely inadequate for their role. Despite numerous operations and reasonable success against German traffic, the Soviet navy lost only a single boat, rammed by a German torpedo boat in the final phase of the Baltic submarine war.
Due to losses and insufficient construction, the nominal strength of all named flotillas never exceeded fifty ships during the war. With the operational strength usually well below that figure, only important convoys and large merchant vessel or warships were escorted by subchasers while smaller vessels were routed independently or escorted by minesweepers and smaller patrol vessels. In 1941 a contract for twenty-five war subchasers (Kriegs-U-Jäger), displacing 830 tons standard, was assigned to five building yards. Representing the only purpose-built class of ASW vessels constructed for the German navy during World War II, the first of its class was commissioned on 11 March 1943. A total of nineteen were commissioned during the war with the rest still incomplete in May 1945. The coal-burning vessels carried six depth charge throwers (DCT) and 120 charges but were much slower than similar Allied designs like the British Flower-class corvettes. None sank an Allied submarine.
The lack of adequate ASW vessels, trained personnel, and offensive combat tactics was reflected by the small number of submarine sinkings by naval and air force units in all theaters of combat. Out of the ninety-four Allied submarines lost, surface ships sank only twenty-five (see table 2.1). Designated antisubmarine vessels accounted for 80 percent of these with the rest coming from torpedo boats, minesweepers, and other small units. In the absence of a naval air force command, the Luftwaffe never committed to ASW. Consequently, aircraft were not a serious threat to Allied submarines. Defensive mine barrages proved to be a most effective submarine-killer, especially in the Baltic, the Black Sea, and along the Norwegian coast. However, apart from the Mediterranean, where the operational situation favored the use of submarines, German shipping losses to submarine attack remained small throughout the war. Allied submarine operations never impaired the vital transport of iron ore from Scandinavian ports or the supply of the German garrison in Norway and the Arctic theater.
4. Submarine
At the outbreak of war, German U-boats were a vital part of the commerce doctrine envisaged as the Kriegsmarine’s main offensive role. While enemy warships were considered targets of opportunity, doctrine designated merchant vessels as the U-boat’s prime targets.
TABLE 2.1 Allied Submarines Sunk by German Antisubmarine Operations during World War II
The concept underlying Germany’s doctrine of tonnage warfare was quite simple: to reduce enemy shipping below the minimum level required to sustain short- or medium-term economic survivability by sinking more tonnage than was replaced by new construction or through other means. The strategy’s main flaw was the lack of reliable statistics and insight into Britain’s economic situation. While the German naval staff over the years produced steadily rising target figures required for achieving victory in tonnage warfare, actual successes at sea never approached these targets. When this was realized at the beginning of 1943, and with Germany by then pressed into a defensive role on almost all fronts, the tonnage warfare concept was amended by introducing the concept of supply warfare. This aimed to reduce the material flow, especially from the United States, toward Allied forces poised to attack the German position on the European mainland.
Correctly expecting the Royal Navy to introduce convoys upon the outbreak of war, Dönitz developed the nighttime surface group or wolf pack attack tactic in 1935. Based on lessons from the last years of World War I, this tactic was designed to overcome the problems associated with locating a convoy and to offset the expected concentration of escorts. Advantages in radio communications during the interwar period enabled a U-boat group to be led by a commander embarked on one of the boats or by a central shore command. Control of individual boats usually ended when a boat contacted the enemy. Thereafter, the boat’s commanding officer enjoyed full freedom of maneuver.
5. Amphibious Operations
The German navy conducted one major amphibious operation in the First World War. The landing on the Russian island of Ösel in the Baltic in 1917, protected by a large contingent of the High Sea Fleet, was well prepared and a complete success. The transport ships were unloaded by barges and unpropelled landing boats, which were pulled by wire lines through the surf.
Little was done to advance amphibious doctrine or capabilities between the wars. The Norwegian landings were accomplished without special equipment, relying on surprise and the country’s weak defenses for success. With the unexpectedly quick defeat of France, preparations for an invasion of Britain commenced. In only three months, the Kriegsmarine improvised a landing fleet of 2,000 converted river barges and 170 transport ships. This effort included the development of a tank landing craft, the Marinefährprahm (ferry lighter) driven by three truck engines, which could lift three medium tanks. Some 720 were built during the war.
Although Germany’s improvised amphibious fleet was never tested on Britain’s shores, the Kriegsmarine proved adept at conducting landings. Although flotillas of Greek caÏques and small steamers carrying troops against Crete in May 1941 fell afoul of British naval forces tipped off to their presence by signal intelligence, operations against the Soviet Union were more successful. Using Marinefährprahm (MFP) barges along with small army and Luftwaffe landing craft, German forces captured the large Baltic islands of Ösel, Moon, and Dagö in September 1941. German forces leapfrogged the Kerch Strait from the Crimea into the North Caucasian area in 1942 using MFPs, Siebel ferries (another type of invasion barge consisting of a pair of steel pontoons), and army landing craft. In 1943 in the Aegean, German forces overcame British naval superiority and made a number of highly successful landings, including opposed assaults against the islands of Kos in October and Leros in November. In the Adriatic in 1943, the navy ferried battalion-sized forces against the Dalmatian islands occupied by partisan forces after Italy changed sides. There was also an unsuccessful landing on the Finnish island of Suursaari in 1944. These operations were all distinguished by effective navy-army–air force cooperation. The Aegean operations even included paratroop drops.
German forces likewise conducted successful amphibious evacuations including Sicily in August 1943 and Sardinia and Corsica in September–October 1943. In late 1943 the navy withdrew 450,000 German and Axis troops back across the Kerch Strait. The crossing of the river Schelde in Belgium and the Lyngenfjord in northern Norway were also conducted using landing craft.
6. Trade Protection
Except for a few blockade-runners, the Kriegsmarine could not maintain its Atlantic trade routes against the British blockade. However, small convoys, generally escorted by minesweepers, or armed trawlers traversed the coastal waters of German-held Europe, and the Kriegsmarine successfully protected the decisive iron ore trade from Narvik and Lulea, Sweden. The Narvik route was especially important in winter when the Baltic froze. Minefields protected the route along the Norwegian coast, and it was only in 1944 that British air attacks were able to inflict major losses on the convoys. Mine and net barrages laid in the war’s opening days effectively sealed the entrances to the Baltic. In 1941 a mine barrage across the Gulf of Finland blocked in the Russian fleet. In the summer of 1942 some Russian submarines penetrated the barrage and sank several German and Swedish cargo ships. In response, a 60-km-long antisubmarine net was laid in the spring of 1943, which was renewed after the spring 1944 thaw, effectively sealing the gulf until the autumn of 1944.
The Allied blockade against German shipping quickly dried up the import of raw materials and other goods from overseas countries, and by early 1941, Germany’s available stocks of strategic raw materials, especially natural rubber, had drastically declined. The persistence of the British defense as well as German preparations for the Russian campaign compelled Germany to find new ways to import more materials to maintain war production. Soon Berlin’s interest turned entirely to its Axis partner, Japan. Up to mid-1942 eleven German and Italian ships lying idle in Far Eastern ports since the outbreak of war ran the blockade and reached Bordeaux from Japan with 74,960 tons of urgently needed raw material, half of it rubber. Three ships were sunk and one turned back. Due to increased Allied surveillance of the main shipping routes, only four of thirteen ships carrying 29,600 tons reached Bordeaux in the following 1942–1943 blockade-runner season. Blockade running using merchant vessels was abandoned in January 1944 after only one of five ships sailing in the 1943–1944 season arrived. Submarines offered the only alternative to maintain the flow of the most urgently needed raw materials from the Far East. However, repeated attempts in 1944–1945 were frustrated by Allied antisubmarine operations. Only four German and one Japanese submarine, carrying a mere 611 tons of material, completed the trip to Europe, with two more still en route at the time of Germany’s capitulation.
7. Communications
From 1927 the Kriegsmarine maintained modern long- and shortwave transmitters at Kiel that could communicate with ships around the world. A special long-wave transmitter was built at Kalbe for submarines. Even submerged submarines could receive its signals. The ships were provided with standardized transmitters and receivers for long- and shortwave. For smaller units and planes, a 40–70 watt radio set from Telefunken worked very well. An ultra-shortwave radio was introduced for short-range voice communications.
A. SHIPS
After the defeat in the First World War, the Treaty of Versailles limited the strength of the new Reichsmarine in numbers and in the displacement of new construction:
The construction or acquisition of submarines and aircraft was forbidden.
The Reichsmarine could equip itself with only a handful of very old Kaiserliche Marine ships including eight pre-dreadnoughts of the Braunschweig and Deutschland classes launched between 1902 and 1906, eight old cruisers launched between 1899 and 1903, and thirty-two pre–Great War torpedo boats. Due to treaty limitations on the number of personnel, only a few of these ships could be manned at any one time—for example, no more than four of the pre-dreadnoughts were ever simultaneously active.
The construction of the first replacement vessel, the cruiser Emden, started in 1921 and took almost four years due to political and financial reasons. She combined a mixture of proven and innovative elements. The hull lines resembled those of the last of the Kaiserliche Marine cruisers whereas the structure was almost all welded, the first large ship worldwide to be so constructed.
In 1925 Möwe, the first replacement destroyer, was laid down. A real destroyer design on 800 tons appeared impossible; consequently, she and her eleven follow-ups were classified as torpedo boats. The hulls of these boats were also partly welded.
In 1926 the next cruiser replacement program started. This consisted of the three K-class vessels followed by Leipzig and Nürnberg (ordered and laid down in 1933). These cruisers had an adequate main armament of three triple turrets with 15-cm guns but suffered from light construction, and their high length-to-beam ratio affected stability.
The battleship category presented the most difficult replacement dilemma. Since a battleship design of 10,000 tons was impossible, difficult discussions took place over eight years regarding a range of ideas from a heavily armed monitor to a cruiser-like ship. The remarkable result was the Deutschland class, classified according to the terms of the Treaty of Versailles as a Panzerschiff (armored ship). On a 10,000-ton standard displacement (actual standard displacement ranged from 10,600 tons for Deutschland to 12,340 tons for Admiral Graf Spee), these vessels carried six 280-mm guns, giving them firepower superior to the “Treaty” cruisers of other navies, which were limited to 8-inch guns. Their newly developed diesel propulsion gave them a speed of twenty-eight knots—faster than most existing battleships—and enabled them to sail 10,000 nautical miles at twenty knots. They were ideal for commerce warfare and well suited for missions in home waters. Soon the term “pocket battleship” (partly ironic, partly respectful) was coined to describe them.
In the meantime, many of the old ships found their way to the breaker’s yard. Some others were modernized or reconstructed for different duties and saw service during the Second World War.
Two months before Deutschland was commissioned, Hitler came to power. At first the new government’s direct influence on the Reichsmarine’s building program was not obvious. But behind the scenes considerable enhancements were made to the Panzerschiff design. The next two ships were laid down early in 1934 to an official displacement of 18,000 tons. Since only the defensive characteristics were improved, discussions continued. Finally, in mid-1934, construction was halted and these ships were again laid down in May and June 1935 to an even larger design, emerging as the battleships Scharnhorst and Gneisenau. This convoluted development produced handsome but compromised vessels.
At this time Hitler renounced the Treaty of Versailles and entered into the Anglo-German Naval Agreement three months later. This allowed Germany to build a fleet 35 percent of the British navy’s strength. The 35 percent limit was valid for each category except the submarines, where the parties agreed upon a 45 percent (later up to 100 percent) limit. Germany’s building program was designed around these levels.
At the end of 1938 a new shipbuilding program on a massive scale was being discussed (see table 2.2). Hitler approved this program (called the “Z-Plan”) in January 1939 and terminated the Anglo-German Naval Agreement in April 1939. Only a few of the new Z-Plan ships were laid down and, after the outbreak of war, they were broken up on the slip, including aircraft carrier B and light cruisers M and N (see table 2.3).
Some general technological aspects of the shipbuilding program deserve mention. High-tensile steel St 52 was extensively used for hulls. In certain areas, homogeneous armor was used as structural material, especially the new developed types Wotan hart and Wotan weich. These were chromium-nickel-molybdenum steel alloys with a much higher tensile strength than their predecessors. Welding was extensively employed on smaller units to save top weight. The development of suitable diesel engines took some time, and the required power was not available for the new battleships and cruisers. Only the battleships of the planned but never built “H” class would have received diesel engines. In the meantime, great hopes were placed on a high-pressure steam system. But this ultimately resulted in fragile and uneconomic power plants. Only later installations showed satisfactory reliability.
The most powerful machinery belonged to the aircraft carrier Graf Zeppelin. Although almost completed, this ship never saw service.
Scharnhorst and Gneisenau were enlargements of the Panzerschiff concept. The main fault of these relatively large ships was their insufficiently powerful main armament. An exchange of the three 280-mm triple turrets to three 380-mm twin turrets was planned. Only Gneisenau started reconstruction; this commenced while she was under repair from a bomb hit in 1942, but the project was eventually abandoned.
The follow-up battleships, Bismarck and Tirpitz, were excellent warships and comparable to modern battleships in other navies. They were well armed with a main battery of four 380-mm twin turrets, and their protection was at a high standard.
The Panzerschiff proved a useful type for the Kriegsmarine. Their very long range made them ideal for oceanic operations. In contrast, the high-pressure steam system used by the heavy cruisers proved unreliable and suffered from limited range. Machinery problems also hampered the destroyers and new torpedo boats. Another problem was the unsatisfactory seaworthiness of these ships although some improvements would be achieved during the war.
TABLE 2.2 Germany’s Naval Construction Program, Orders up to the End of 1938
a In addition to Scharnhorst and Gneisenau.
b Of a special type ordered in 1938.
c 2 Type I, 32 Type II, 42 Type VII, 22 Type IX.
TABLE 2.3 Major Warships as of 1 September 1939 and Wartime Additions
Eventually, Germany’s main instrument of naval power proved to be the submarine. With 659 built, the Type VII C boat was the most numerous. It carried five torpedo tubes and up to fourteen torpedoes on a surface displacement of 760 tons. The 141 Type IX C boats conducted oceanic operations. They had six torpedo tubes and carried up to twenty-five torpedoes at a surface displacement of 1,120 tons. The Walter U-boats performed in trials only; the revolutionary Type XXI (118 completed) and XXIII (60 completed) boats saw only sporadic service in the war’s last days.
In addition, the Kriegsmarine deployed a great number of smaller warships, amphibious vessels, and auxiliaries. These vessels played an important role in the navy’s war effort.
B. AVIATION
1. Ship-based
In 1939 the Kriegsmarine had two squadrons with Ar196 and He60 in Bordfliegerstaffel 1/196 and 5/196 for use aboard battleships, cruisers, and armed merchant cruisers. For the projected aircraft carriers, a carrier group (Trägergruppe) II/186 was established at Kiel-Holtenau with three squadrons 4th/186 (Ju87C) at Stolp and at Brüsterort 5th/186 and 6th/186 (Bf109T). They were trained for catapult takeoffs and engaging arrestor wires to land. The Ju87s helped sink the Polish destroyer Wicher and minelayer Gryf at Gdynia. Soon after, the group was dissolved as the completion of the carrier was postponed.
2. Shore-based
The shore-based squadrons established by 1939 included Küstenfliegergruppe (KG) 106 with 1st/106 (He115) and 2nd/106 (Do18) at Norderney and 3rd/106 (He59) at Borkum; KG 406 with 1st/406 (He60), 2nd/406 (Do18), and 3rd/406 (He59) at List/Sylt; KG 306 with 1st/306 (He60) and 2nd/306 (Do18) at Dievenow; KG 706 with 2nd/706 (Do18) and 1st/706 (He60) at Kamp; and KG 506 with 1st/506 (He60) and 3rd/506 (He59) at Pillau, 2nd/506 (Do18) at Kamp, and 3rd/706 (He59) at Dievenow.
All units reported to the general of the Luftwaffe as commander in chief Kriegsmarine, General Major Hans Ritter. There were FliegerfÜhrer (air command) west at Jever and east at Dievenow. Tactically they were under Kriegsmarine command. The air force and navy constantly bickered over the command of these units, and the air force generally prevailed. When KGs 106, 606, and 806 got new land-based planes (He111 and Do17Z), the Luftwaffe obtained command and used them for their own purposes. The Kriegsmarine retained only floatplanes and flying boats for reconnaissance, rescue, and escort duties.
Nevertheless, a long-range bomber group, I/KG 40 came under navy command in January 1941. It was operated by the FliegerfÜhrer Atlantic under Luftflotte (air fleet) 3 and flew reconnaissance and bombing missions for Naval Group West and especially for commander U-boats. The planes were four-engined FW200, Ju290 (radar equipped since mid-1943), the new long-range bomber He177 Greif, and some Do217 E-5s. However, KG 40’s deployment requirements were never met and the group did not achieve the desired results. Another unit frequently used over the sea was KG 100 equipped with Do217 E-5s and later with the He177. From 1943 both units deployed the Henschel Hs 293A radio-controlled missile and the unpropelled FX 1400, also called the “Fritz X.” The radio-controlled bomb’s first kill was the British sloop Egret on 27 August 1943 in the Bay of Biscay. On the same mission, a destroyer and a sloop were damaged. KG 100’s most famous kill with the “Fritz X” was the Italian battleship Roma on 9 September 1943. Using these weapons, groups II and III of KG 100 accounted for eight merchant ships of 68,000 GRT, ten destroyers, one landing ship tank (LST), two landing craft, tanks (LCTs), and one hospital ship sunk. They damaged two battleships, three light cruisers, twelve destroyers, and twenty-seven merchantmen.
During the war, Germany used roughly five hundred Hs 293s and “Fritz Xs” and observed about a hundred hits. The ratio would have been higher with better-trained operators.
For operations over the Baltic Sea, a FliegerfÜhrer Baltic was created under Luftflotte 1. It contained KG 806 (Ju88); Seeaufklärungsgruppe (SG) (He114, He60, Ar95), 1st/Fliegergruppe 196 (Ar196); and KG 506 (Ju88). This formation was dissolved in October 1941 and only one squadron of seaplanes, 1st/Fliegergruppe 127, remained in Estonia under Luftflotte 1.
After the Battle of Britain, Luftflotte 5 in Norway deployed seaplane squadrons at Stavanger, Trondheim, Tromsö, and Kirkenes. From spring 1942, when operations against the Allied convoys to Murmansk became important, Luftflotte 5 received KG 30 (bombers) and 26 (torpedo planes), but after the Allied November 1942 landings in North Africa, these two units relocated to the Mediterranean. The seaplanes were reorganized in 1943 and formed into SG 130 and 131 with BV138 three-engined and BV222 long-range flying boats. Luftflotte 5 had Ju87s for short-range missions as well as Ju88, Ju188, He115, and He111s. The latter four types were used mainly for torpedo missions.
In December 1940, Luftflotte 2’s X.Fliegerkorps deployed in Italy, and from April 1941 the 7th Seenotstaffel (rescue) and the SG 126 (reconnaissance) operated over the Aegean. Upon reaching the Black Sea, Luftflotte 4 was given SG 125 with 1st and 3rd /125 squadrons containing twenty-five planes from the Baltic. They were first based at the Crimean Peninsula but redeployed to Constanta, Romania, in May 1944. The commander, chief of aviation Crimean, later chief of aviation Black Sea, also had the 8.Seenotstaffel and a squadron of minesweeper planes.
The number of planes of the naval air arm never exceeded two hundred, some 5 percent of Luftwaffe strength.
C. WEAPON SYSTEMS
1. Gunnery
Surface. Some years before the First World War, the German navy took the necessary steps to achieve good long-range gunnery results employing rangefinders. The excellent shooting of the German battle cruisers and battleships at Jutland is well known. Nevertheless, during some of the battle’s phases, the Germans did not fire due to an absence of central fire control. After the battle, the development of such equipment was considered imperative. However, not all ideas could be developed and tested before the war ended.
The Reichsmarine tried some improvements on fire control starting in 1921. A more extensive test program with newly developed equipment was started in 1927 on the old battleship Schlesien.
Also in this period the first new guns were developed. Many more followed in the 1930s. The design was an improvement of a well-tried formula. German heavy guns were built up from shrunk-on tubes and had a wedge breech. The main propellant was contained in a brass case. The shells were much improved. Streamlining increased impact velocities. Krupp was the main manufacturer for the larger guns, and Rheinmetall made the smaller ones. See appendix I for a listing of major naval guns.
In the area of fire control, creativity was strongly emphasized; therefore, improvements could be made on almost every new ship. A drawback of this policy was that it resulted in a variety of equipment.
The most advanced fire-control set was the surface gun director (Seeziel-Feuerleitanlage) C.35. The main components were a target transmitter, an angle resolver, a gyro platform, a speed sensor, rangefinders, and a fire-control computer. The rangefinders were stereoscopic instruments from Zeiss with different base lengths (the rangefinders of the main fire-control stations and in the turrets B, C, and D on Bismarck were 10.5-m instruments).
The first operational radar to be embarked was the FuMO 22 (Seetakt) from GEMA installed on the Admiral Graf Spee early in 1938. Subsequently all major warships carried radar. Nonetheless, the Kriegsmarine was slow in adopting radar and in training officers in its use. A special branch for officers was not established until the end of 1941 when a school was also opened at De Haan near Ostend, Belgium. Instructions were only provided at the end of 1943.
Operationally, radar was used for detection. In 1943, Scharnhorst and possibly Admiral Scheer conducted gunnery trials using radar to spot the fall of shot. Scharnhorst was equipped with FuMO 26 (Seetakt) at that time. The accuracy of FuMO 26 is reported as ± 70 m in range and ± 0.25° (which corresponds to ± 65 m at a range of 15,000 m) in direction. The results were reported as good. The cruiser Nürnberg achieved excellent results during a test firing against the target ship Hessen in December 1944.
Bismarck used her radar’s search function in her night action against British destroyers, as did Lützow during the 1942 action against convoy JW51B. However, although she had the means for radar-assisted gunnery, Scharnhorst did not use radar at all in her last battle fought in December 1943 in the belief that this would disclose her location. This omission proved fatal.
Antiaircraft. Some Kaiserliche Marine battleships were equipped with antiaircraft guns. The 88-mm S.K.L/45 was the basis for the further development in the 1920s and 1930s. Barrel and breech followed similar guidelines as the low-angle guns. Differences were in the rate of fire and the mountings. The AA gun mountings were preferably triaxial.
The navy went through a lengthy and never completely successful process to achieve a satisfactory high-angle fire-control system. It went to war with gyro-stabilized AA control stations; the last two versions, SL6 and SL8, were fitted with spherical armored hoods over 4-m stabilized rangefinders. The SL6 was direct-stabilized with large gyros and heavy balancing weights. The later SL8, in contrast, used small gyros with control loops. Due to the unchanged outer structure, ballast replaced the balancing weights. A technical authority of the Kriegsmarine criticized this before World War II and presented a more modern solution, but his proposal was not acted upon until 1942. Most likely this AA control station (Flakleitgerät M42), now with radar, was fitted as a prototype on Emden at the end of the war.
Details of Bismarck’s AA system can serve as an example of the problems in this field. Bismarck had different types of 105-mm AA gun mounts (Type C.33 and C.37) for the forward and aft batteries. These mounts had different training and elevating rates, which the fire-control system could not compensate for. This meant that targets on one broadside could not be engaged by all guns under one director. Tests with the SL8 AA control stations (there were only two of the planned four on board) were unsatisfactory. The test team made some suggestion for improvements. But they also stated that a complete correction of the flaws could be achieved only with a reconstruction. The condition of Bismarck’s AA fire-control system during Operation Rheinübung was insufficient and may have been one of the reasons for the aerial torpedo hit that ultimately doomed her.
2. Torpedoes
The Kriegsmarine introduced two basic dual-purpose 533-mm torpedo models for use on U-boats and surface vessels, both measuring 7.163 m in length and carrying a 280-kg explosive charge. They were developed in the early 1930s, and the first were delivered to the navy in 1934. The air-driven model T-I (or Type G7a) had a top speed of forty-four knots for a running distance of some 6,000 m but could be dialed down to thirty knots and 12,500-m running distance. The design was plagued by engine defects and a tendency to run deep. The propulsion problems were not rectified until 1939, but depth-keeping failures continued well into 1940.
The battery-driven electric torpedo model T-II (or Type G7e) was more reliable and much cheaper to produce than the Type G7a. Originally intended for use on U-boats, it was capable of only thirty knots at maximum for a running distance of 5,000 m. The electric battery required maintenance every three to four days. Running virtually invisible without the telltale stream of bubbles to alert ships, it eventually became the standard U-boat weapon and was also used by surface ships.
At the start of the war about fifteen hundred of the two models were available for combat use with about the same number in production. Both models were equipped with the standard combined impact/magnetic proximity detonator. High hopes had been placed on the new magnetic detonator, which was to explode below the target to break its keel. However, in the first months of the war numerous malfunctions in frontline use took place, which climaxed during the Norwegian campaign in April–May 1940, when U-boats lost a number of opportunities to score hits upon British capital ships. During a subsequent court-martial of high-ranking officers in the relevant torpedo departments, it was found that the torpedoes and pistols had been declared ready for operational use despite insufficient testing. Faced with the impossibility of improving the design on a short term, the Kriegsmarine had no alternative but to return to the old impact exploder, which, after some improvements up through summer 1940, became the standard German torpedo pistol for the next two years.
Only at the end of 1942 did an improved model of a combined impact/magnetic detonator became ready for frontline service. The Type G7e torpedo fitted with this pistol received the model designation T-III. At the same time, a newly designed spring apparatus guidance system (FAT) allowed the torpedo to run patterns, which theoretically increased the probability of hitting the target under increasingly difficult combat conditions. To improve the performance of the G7e torpedo in the FAT mode, its battery was enlarged in 1943, allowing it to run 7,500 m at thirty knots. This design became known as model T-IIIa. In February 1944 the more sophisticated LUT guidance system was introduced. It allowed torpedoes to follow a spiral pattern independent of the target angle at the time of launching.
In parallel, the Kriegsmarine had worked since 1935 on the development of an acoustic homing torpedo based on the design of the air-driven G7a and for use by U-boats against fast-running warships. In 1940 the focus was shifted to targets running at medium speed, which allowed the use of the G7e design. Following frontline tests with U-boats in February–March 1943 with the prototype T-IV code-named “Falke,” the new model T-V “Zaunkönig” was introduced in August 1943. High hopes for a renewal of the U-boat offensive in the Atlantic following the temporary withdrawal in May of the same year remained unfulfilled despite a number of successful shots. Postwar evaluation proved that only 15 percent of all T-V torpedoes fired by U-boats during the war actually hit the target. Successful Allied countermeasures, such as simple towed mechanical noisemakers, and existing design flaws prevented a higher success rate. The T-V was later also adapted for use by surface vessels, especially by schnellboot, or S-boats. At the end of the war the improved T-XI model (Zaunkönig II) was ready for use on U-boats, but hostilities ended before any could be used.
Numerous other passive and active torpedo homing and steering designs were projected or tested, but none became operational. The same applies to large-scale experiments with new propulsion systems using hydrogen peroxide or closed-cycle motors. Many of these developments pioneered postwar designs in Allied navies.
Exact figures on the total German torpedo production during the war are not available, but it appears that more than 50,000 torpedoes of all types were built. Of these, more than 13,000 were fired in anger by the end of November 1944 with U-boats accounting for about two-thirds of the total.
3. Antisubmarine Warfare
A great deal of work in the field of underwater acoustics was preformed using passive sets. One such set was called GHG (Gruppenhorchgerät) and consisted of two rows (one per each side) of Rochelle salt receivers in the forward part of a ship. The bearing of an incoming sound wave was detected by the processing of the signal delays in a compensator. All U-boats and most surface warships were equipped with GHG. An advanced version was fitted in the heavy cruiser Prinz Eugen. This set consisted of two rows with sixty Rochelle salt hydrophones at each side, arranged in an elliptical array on her bows. Before the battle of the Denmark Strait Prinz Eugen’s GHG tracked the Hood well over the horizon.
First steps toward the development of an efficient underwater detection system began in 1933, using a French Langevin set with piezo-electric transducers aboard the experimental vessel Grille and the Finnish submarine CV 707 as target ship during her builder’s trials in the eastern Baltic. However, the Germans were unaware of the poor conditions for sound propagation in this brackish, heavily layered body of water, and trials proved unsuccessful until shifted to the North Sea.
During the following years work concentrated on the development of an active acoustic location device, designated S-Gerät (Sondergerät), using magnetostrictive transducers. Following the manufactor of ten experimental sets in 1937, an additional nineteen were delivered to the navy during the summer of 1939. Of these, thirteen sets were installed on various vessels and the rest allocated to training establishments ashore. Antisubmarine fire-control systems were nonexistent at that time. At the start of the war, there existed almost no practical experience on their use, and the training of operators was in its infancy. Hydrophone or passive listening gear still formed the backbone of underwater location technique. By the summer of 1940 just ninety-one S-Gerät sets for installation on surface vessels were completed. Concentrating on the basic design features, production of a simplified version (Mob-S-Gerät) was started, of which almost fifteen hundred sets were delivered by the end of 1942 and installed on various classes of vessels.
4. Mines
German anchored mines were improvements upon turn-of-the-century weapons, the most common types being EMC and EMD. The EMG was developed for areas with a great tidal range such as the English Channel. The mine was loosely anchored and suspended from a small float. Special antisubmarine mines were the UMA, UMB, and UMC types. Usually they had upper and lower antennas to detonate the mine if a submarine passed over or under the mine itself. This did not always lead to the submarine’s destruction if she was too far away.
A magnetic fuze for mines was developed in 1929. Called the BIK, it used the deviation of the Earth’s magnetic field caused by a nearby steel ship and had at first to be adjusted to the local magnetic field by hand. A later type introduced in 1940, the SE-BIK, was self-adjusting. It was used for aircraft mines (LMA, LMF), which were dropped with a parachute, and for submarine mines (TMA, TMB, TMC), which were discharged through the torpedo tubes. Most were ground mines with a depth up to 40 m with a heavy explosive load of 300 to 935 kg, but TMA was anchored. By the end of the war, ground mines were provided with combined acoustic, magnetic, and pressure fuzes.
Germany used 223,000 mines in the Second World War compared to 263,376 British, 54,457 Italian, and 40,000 Russian mines. The British lost 281 warships and 296 merchant vessels on German minefields. The Kriegsmarine used mine destruction vessels (Sperrbrecher) with strong electric magnets against magnetic mines. There were enough large merchant vessels idle to permit such use.
D. INFRASTRUCTURE
1. Logistics
From 1933 Germany began to expand oil production by increasing exploration and introducing synthetic production from coal (distillation or hydration). Nevertheless, the Kriegsmarine had difficulties meeting its demand for heavy fuel oil from hydration as this method mainly produced light oils (gasoline). In 1936 German oil production covered only 12 percent of the Kriegsmarine’s diesel requirement and 31 percent of its fuel oil demands. By 1938 production met 22 percent of the diesel and 22 percent of the fuel oil requirements. According to agreements with the Kriegsmarine, the Deutsche Erdöl AG (DEA) began to build oil distillation plants from which the navy could meet 25 percent of its fuel oil requirements during the war. Another 50 percent could be covered by tar oil from hard coal mined in the Ruhr and Silesia.
Because of these production limitations, the Kriegsmarine started to import and store oil in so-called Ölhäfen, large, underground oil depots, and in other depots during the prewar years. The construction of Ölhäfen started in northern Germany in 1937. By the time of their planned completion in 1943, they were intended to have a capacity (by volume) of 10 million metric tons, but by 1939 only a capacity of 1 million tons had been completed.
When the war started, the Kriegsmarine’s fuel situation was good because of its foresight and stockpiling: the 770,000 metric tons of diesel that had been accumulated were expected to last thirty-nine months (given an expected monthly consumption of 20,000 tons), and 450,000 metric tons of fuel oil were projected to last for more than three months (given an expected monthly consumption of 137,000 tons). These estimations proved too high because there were fewer new ships commissioned and less activity than expected in the war’s first six months. Oil stocks captured in the Netherlands and northern France offset the Kriegsmarine’s own consumptions and its deliveries to the army. Therefore, until the summer of 1941, there were no shortages.
With the beginning of the campaign against the Soviet Union in June 1941, oil reserves began falling, and the drop accelerated with deliveries to the Italian navy, which began at the end of 1941. From September 1941 until August 1943, Italy received 425,000 tons of fuel oil from Kriegsmarine stocks, an amount that equaled more than a quarter of the Kriegsmarine’s own consumption during that period (1,600,000 tons). Moreover, the extended area of operations—from the Atlantic coast at the Franco-Spanish border up to Norway’s North Cape—proved troublesome and the long distances between the bases and ports affected the accumulation and distribution of supplies. Because all bases had to have a certain minimum stock of oil, supplies often were not at the place where they actually were needed and problems occurred more frequently. From the summer of 1941 river barges had to transport oil in the western areas because all tanker wagons had been withdrawn to the east. This increased transport time by a factor of two or three, which reduced flexibility and availability. After 1941 shortages of fuel restricted the navy’s operations. From the beginning of 1942 there were less than 200,000 tons of fuel oil, and from the summer of 1942 there were less than 100,000 tons of diesel, which was the minimum reserve for each.
In the context of logistics, the decommissioning of the heavy units that Hitler ordered at the beginning of 1943 had a special significance because their activity depended upon the availability of oil. The Kriegsmarine tried to become more oil independent by building and commissioning coal-fired ships. The Type 1940 minesweepers, which from 1942 assumed many tasks usually performed by larger units, were the Kriegsmarine’s best-known coal-fired ships.
The fuel situation improved at the end of 1943 (see table 2.4). After Rome sought an armistice with the Allies, there was no longer a need to deliver oil to Italy, and fleet consumption dropped because the Kriegsmarine’s larger warships undertook fewer missions. Production of synthetics provided 7,500 tons oil a month in 1944 compared to only 1,500 tons in 1942. When the oil fields in Romania, which had covered 45 percent of the requirements, were lost in 1944, the situation deteriorated again. Fuel reserves and distribution influenced operational planning during the entire war.
For the replenishment of ships at sea, so called Troßschiffe (supply ships) were deployed. The Kriegsmarine had tested their use during the Spanish Civil War. However, a building program started in the mid-1930s was not complete at the beginning of the war. One of these purpose-built supply ships was the Altmark, which became famous through its association with Admiral Graf Spee. In February 1940 a party from the British destroyer Cossack boarded her in Norwegian waters.
In addition to these purpose-built supply ships, suitable civilian ships were used for supply services. After the sinking of Bismarck, the Allies destroyed the German system of floating supply stations by capturing these vessels. For the replenishment of submarines, special types of supply U-boats (Milchkühe) were introduced. But after breaking the German codes, the Allies learned their rendezvous points, attacked the supply boats, and destroyed this system as well.
2. Bases
The Kriegsmarine’s main German bases were Wilhelmshaven for the North Sea and Kiel for the Baltic. At the height of the German expansion, the Kriegsmarine needed to guard more than 18,000 km of coastline. To cover the needs of its ships and vessels, different kinds of bases were established in Germany and the occupied countries:
Kriegsmarine-Werften were fully equipped ship building and repair yards (first-level bases).
TABLE 2.4 Fuel and Diesel Oil Reserves of the Kriegsmarine
Kriegsmarine-Arsenale were efficient and large equipment stores (second-level bases).
Marineausrüstungs- und Reparaturbetriebe (MAUREB) were local naval equipment and repair stores (third-level bases).
Marineausrüstungs- und Versorgungsstellen were local naval equipment and supply stores (fourth-level bases).
Marineausrüstungsstellen (MAST) were local naval equipment stores (fifth-level bases).
The Kriegsmarine had its own naval yards in Wilhelmshaven and Kiel. During the war several more naval yards were established in the occupied countries. The need to transfer personnel from German yards to these new yards slowed work in Germany.
To protect U-boats from air attacks, large submarine bunkers were built along France’s Atlantic coast at Brest, Lorient, St. Nazaire, La Pallice, and Bordeaux starting in 1941. In Norway, bunkers were constructed in Bergen and Trondheim. In Germany, Helgoland, Hamburg, and Kiel received bunkers. Unfinished bunkers included two at Bremen, two at Marseille, and two at Salamis in Greece. For MTBs (S-boats) and motor minesweepers (R-boats), bunkers were built along the Channel coast at Cherbourg, Le Havre, Boulogne, Ijmuiden, and Rotterdam; one at Den Helder remained unfinished.
After 1918 Germany retained only a few coastal batteries: Wangeroog, Borkum, Norderney, Sylt, and Schillig on the North Sea coast, and only Pillau on the Baltic coast. Helgoland and the western Baltic coast could not be armed because of treaty restrictions. This changed after 1933.
The occupation of much of Western Europe made new demands on Germany’s coastal defenses. The Kattegat was protected by two 380-mm batteries at Kristiansand, Norway, and Hanstholm, Denmark. Narvik had two 406-mm batteries originally intended for battleship H. In the last phase of the war, two 280-mm triple turrets from the damaged Gneisenau were placed near Trondheim and Bergen. A large number of medium batteries guarded the coastal shipping along the Norwegian coast. The heaviest fortification was built in autumn 1940 around Calais, France, for the planned landing in England with six heavy batteries from 240 mm to 406 mm. Most of them came from German bases. The Channel Islands were also heavily armed. The biggest battery there was Mirus with four 305-mm guns from the Russian battleship General Alexeiev. The French Biscay bases were protected by one heavy battery each and a number of medium batteries. Brest got a 280-mm battery; Lorient, two 203-mm twin turrets from the unfinished cruiser Seydlitz; St. Nazaire, four 240-mm railway guns in two positions; and La Rochelle, two more 240-mm guns. In the Mediterranean and Black Sea, only medium batteries were used, with two exceptions: Constanta, Romania, with a 280-mm battery, and Chersonnes (Sevastopol), a 203-mm battery.
3. Industry
As demands for iron and steel were higher than the amounts available, a continuous shortage of these materials hampered production from the summer of 1936. For this reason, the Wehrmacht’s focus was on weapons while insufficient ammunition was produced and infrastructure was built reluctantly. The Kriegsmarine was the armed service least affected by this situation because it could always use the long building times of its ships to trump attempts to reduce its allocations. Thanks to preparations, sometimes clandestine, made since the end of the First World War, the Kriegsmarine was able to launch a full-scale building program in 1935 despite a seventeen-year hiatus. Nevertheless the gap between plans and feasibility soon widened, especially since yards, barracks, and depots were affected by iron and steel quotas. In spite of this, the Kriegsmarine was the only one of the armed services to accumulate sufficient stocks of ammunition.
During the first years of the war, the building program could be carried out more or less according to plan, but by the beginning of 1942 resources had to be shifted to army production because of the demands of the Russian campaign. For example, the Kriegsmarine declared a requirement for 300,000 tons of iron for the first quarter of 1942 but was granted only 157,000 tons. To secure the U-boat program, the building of surface units had to be reduced. Repairs took priority over new construction.
From mid-1943 the German war industry had to cope with steadily climbing requirements and growing Allied air attacks. But thanks to an improved organization under the supervision of Minister of Armament Albert Speer and with millions of slave workers from the occupied countries, industry succeeded in meeting the armed forces’ needs. In 1943 industry started to construct vessels such as U-boats and minesweepers in sections that could be delivered from inland factories to seaside assembly yards. In the last stage of the war the increasing bombing took its toll; in the beginning of 1945 the coal and fuel supply broke down and work in the yards stopped.
In all, some forty German yards built for the Kriegsmarine during the war. Many more inland yards and factories were engaged in the building of ship sections or components. Furthermore, more than thirty yards in occupied or allied countries—France, Netherlands, Belgium, Italy, Greece, Denmark, Norway, Rumania, and Bulgaria—worked on German warships. Even Swedish yards constructed motor fishing vessels for the Kriegsmarine.
IV. RECAPITULATION
A. WARTIME EVOLUTION
The war developed slowly after the fall of Poland; Hitler hoped for a negotiated settlement of the conflict, but after Britain and France rejected Hitler’s October 1939 peace offer, Germany gradually introduced submarine warfare and declared a war zone around Britain. The Panzerschiffe Deutschland and Admiral Graf Spee, which were already at sea, were ordered to start operations. The efforts to build a battle fleet had compromised submarine construction, and talks to gain bases in neutral countries were initiated to increase the efficiency of the limited U-boat force. Italy refused because of British pressure, and Spain only allowed secret replenishment in her coastal waters. The best offer came from Russia for a base near Murmansk.
A first successful campaign, one that was surprising effectively even to the Seekriegsleitung, was the offensive use of magnetic ground mines in British waters, even though limited production and lack of Luftwaffe cooperation compromised the results. After a successful sortie by Scharnhorst and Gneisenau against the British blockade in the North Atlantic, the loss of Admiral Graf Spee in the South Atlantic was a severe setback for the Kriegsmarine and clearly showed the limited potential of cruiser warfare against a hopelessly superior enemy.
The Kriegsmarine kept a watchful eye on Scandinavia from the beginning of the war. The import of iron ore from northern Sweden, which could only be shipped from Norway when the Baltic was iced over, was threatened; Scandinavia also offered favorable base locations in the North Atlantic. At first the neutrality of these countries was regarded favorably, but after receiving hints of a planned Allied intervention during the November 1939–March 1940 Russo-Finnish war, Raeder convinced Hitler of the need to invade Denmark and Norway. This invasion, under the code name Operation Weserübung, succeeded but at staggering cost to the navy—one heavy cruiser, two light cruisers, ten destroyers, and a torpedo boat were sunk and the Panzerschiff Lützow (ex-Deutschland) was heavily damaged. The Kriegsmarine had originally intended to send her on an Atlantic operation and had included Lützow in Weserübung only because of pressure from OKW.
In an operation against the Allied supply routes to Norway, the battleships Scharnhorst and Gneisenau sank the British aircraft carrier Glorious but were both damaged by torpedo hits. This displeased Raeder, and he dismissed the fleet commander who had led the sortie, Admiral Wilhelm Marschall.
The occupation of France seemed to offer another opportunity to end the war, but London refused an agreement. The obvious next step was an invasion of Britain. Hitler decided to commence preparations, but the armed forces did not act in concert. The Luftwaffe believed it could bomb Britain into submission, but this effort failed. Then the army and navy became entangled in a lengthy dispute over the size of the bridgehead. The Kriegsmarine believed it would be possible to secure with minefields only a small passage in the Channel narrows, but the army requested an additional landing zone in Brighton Bay for a larger lodgment. A compromise was achieved too late. The decision to cancel this risky operation was understandable. With hindsight, however, it may have been Germany’s only chance to win the war.
By the end of July 1940 it became clear to Raeder that Hitler was considering war with Russia the following summer to acquire resources and secure Germany’s position, even if the United States entered the conflict. Raeder realized that this would leave the Kriegsmarine to continue the war with Britain largely alone. However, with new bases in France and Norway, conditions had significantly improved. The first convoy battles opened the Battle of the Atlantic’s initial phase. Operations against British shipping by the battleships, the Panzerschiff Admiral Scheer and the cruiser Admiral Hipper in the Atlantic and Indian Oceans were also successful.
When Italy joined Germany in June 1940 the Seekriegsleitung developed new ideas: Italy needed help to dislodge the British from the Mediterranean, and Spanish support would be required to take Gibraltar. Cooperation with France was also thought necessary to secure Italy’s positions in North Africa. These ideas, however, did not meet with Hitler’s approval. He deemed the Mediterranean a secondary theater and opposed cooperation with France.
The Italian navy saw its main task as protecting traffic to Libya and disregarded German requests to take Malta and Crete in September 1940 as a precautionary measure. Rome’s offer to send submarines to the Atlantic was readily accepted and resulted in successful operations.
The Bismarck operation marked the climax of Atlantic operations by cruisers and battleships. The original plan was to have all four battleships and the cruisers in the Atlantic, assisted later by the aircraft carrier Graf Zeppelin, to attack convoys even those escorted by battleships. However, the completion of Graf Zeppelin was suspended in 1940 in favor of the submarine program. Gneisenau and Scharnhorst were not ready to go after their successful March 1941 sortie and Raeder did not want to wait for Tirpitz, which would not be ready before the summer of 1941. Thus, only the cruiser Prinz Eugen accompanied Bismarck. Both decisions proved fatal to the operation. The lack of an aircraft carrier was especially decisive. The Kriegsmarine regarded carriers as unimportant until they proved their value in the war, by which time it was too late. Despite her brilliant victory over Hood, luck ran out for Bismarck when a torpedo dropped by a plane from Ark Royal jammed her rudders.
Bismarck’s foray signaled the end of Atlantic operations by the battleships and cruisers. The utility of Brest as a battleship base faded when air attacks there damaged Gneisenau and Scharnhorst. A further setback was the British destruction of the Atlantic supply tanker network. This forced the cancelation of planned operations by Lützow and Admiral Scheer in the autumn of 1941. Following Hitler’s urgent desire to protect northern Norway from a feared British landing, Raeder reluctantly agreed to withdraw the heavy ships from Brest. The February 1942 “Channel Dash,” the breakthrough of Scharnhorst, Gneisenau, and Prinz Eugen from Brest to Germany succeeded beyond expectation, but Germany thus relinquished its ability to conduct the Atlantic war with heavy ships.
Raeder tried in vain to dissuade Hitler from attacking the Soviet Union. Confronted with the final order, the Kriegsmarine contributed only the necessary measures like the mining of the Gulf of Finland to bottle up the Soviet fleet. No suggestions were made to ease the campaign with sea transport. After Russian resistance unexpectedly stiffened in the later summer, a well-organized supply line along the Baltic coast would have provided valuable support to the army’s assault. However, a small scale of sea power had to be established in the Black Sea to support the Romanian navy in the escort of shipping along the conquered coast. Small units like S- and R-boats, small submarines, and MFPs were brought via the Elbe River to Dresden, transported overland to the Danube, and shipped down to the Black Sea. Several MFPs sailed through the Bosporus Strait, painted in civilian colors. In a similar way, light units were transferred from the French Channel coast on the Seine, transported by land to the Rhône, and down to the Mediterranean for the North African campaign.
U-boats made the best use of the new bases on the French Atlantic coast. They had intensively trained in pack tactics during the prewar period, culminating in a full-scale war game under Atlantic conditions in September–October 1938 in the Bay of Biscay. In a May 1939 memorandum Dönitz demanded three hundred frontline boats to achieve decisive results against British commerce in the event of war. However, at the start of hostilities four months later, a mere fifty-seven boats were in commission. Of these, only twenty-four boats of the I, VII, and IX classes capable of operating west of Britain were ready for frontline use.
Although a large U-boat building program was implemented in October 1939, the first large boats did not become available for operations until some fifteen months later (see table 2.5). Until then, U-boat losses and the withdrawal of operational units to train new personnel kept the number of frontline oceangoing boats small. Hence, group operations did not materialize until the summer of 1940, apart from a few ill-fated attempts in the previous months. However, following the defeat of France, the new bases on the Biscay coast changed the situation greatly. By then, even small U-boat groups operating along the western approaches to Britain achieved great success. U-boat pack tactics with surface night attacks rendered British Asdic practically useless. With hydrophones ineffective in the vicinity of a convoy, visual observation offered the only means of detecting a surfaced U-boat at night, but their low silhouettes made this nearly impossible. Without assistance from radar, which was not yet commonly available, the convoy escorts, insufficient in number and often too slow to pursue a surfaced U-boat at high speed, were virtually helpless against nocturnal pack attacks.
The medium-sized Type VIIC boat eventually became the North Atlantic workhorse in anticonvoy operations. The larger, long-range Type IX boats usually operated independently in waters along the American and African coasts. From summer 1943 several of these boats deployed in the Indian Ocean, using bases in the Japanese occupied Dutch East Indies. The appearance of special supply U-boats in spring 1942 greatly enhanced the use of German boats by extending their endurance in operational areas. However, beginning in the second half of 1941, the diversion of significant parts of the U-boat force to secondary theaters like the Mediterranean and the Arctic upon Hitler’s or the naval high command’s direct orders offset these positive developments.
The successful U-boat campaign in the Atlantic until the summer of 1941 and again during operations off the North and Central American coast in the first half of 1942 prevented U-boat Command from correcting the obvious technical and tactical limitations with existing U-boat types. Lulled into security and inactivity by exaggerated sinking figures, both U-boat Command and the naval construction office feared that the introduction of new designs and types would interfere with the momentum gained by the U-boat construction program.
Allied advances in detection technology, especially the use of radar and direction-finding sets, and improvements in ASW weaponry carried by ships and aircraft made existing U-boat types increasingly vulnerable in the following years. Combined with the continuous extension of air support to convoys, by mid-1942 the productive operational area for U-boat groups was reduced to the central North Atlantic, known as the “Black Gap” area. When escort carriers finally closed this gap in May 1943, pack tactics with the available U-boat types came to an abrupt end, despite the fact that Dönitz could muster a record 236 frontline boats at the beginning of this month. The existing U-boat types were now technologically outdated and suffered grievous losses. This quickly resulted in a shortage of experienced officers and men badly needed to man new boats completing in home yards.
Manning the large number of U-boats with experienced personnel was always a serious problem. From January 1944, even commanding officers hastily drawn from other service branches lacked U-boat experience. Undoubtedly, this increasing lack of combat savvy in the U-boat arm contributed to the horrific loss figures in the submarine campaign’s final two years.
Belatedly, a radical change of opinion toward novel designs and propulsion systems took place at higher command levels during the summer of 1943. This led to the development of true submarines capable of high underwater speeds in a remarkably short period; but even with innovative construction methods, the new type XXI and XXIII U-boats could not be produced in time to reverse the tactical situation. The introduction of snorkel equipment in early 1944 enabled the old U-boats to travel or charge batteries using diesel engines while submerged at periscope depth, which drastically reduced the effectiveness of ASW aircraft. To tie down Allied antisubmarine forces, U-boat command continued operations in the North Atlantic and the European shelf areas until the end of the war but was never able to regain the initiative or interfere with Allied intentions despite severe losses.
TABLE 2.5 Nominal and Operational Strength of the German U-boat Arm during World War II
S-boats were developed as a means for the Kriegsmarine to contest superior sea power in coastal waters using hit-and-run tactics. Nearly a hundred tons bigger than their British counterparts during the first years of the war and equipped with diesels rather than the more sensitive British gasoline engines, S-boats operated effectively in the Channel and the British east coast. They were most effective during the war’s first two years and in 1940 sank three destroyers and twenty-six merchant and auxiliary vessels displacing 49,985 GRT. In 1941 they accounted for one destroyer and twenty-nine merchant vessels of 63,081 GRT in the same area. Twelve more merchant vessels displacing 50,396 GRT sank on their mines. In 1942 in the Channel and North Sea, they sank two destroyers, one motor gunboat (MGB), one minelayer (ML), and nineteen merchant ships displacing 33,049 GRT; five more with 14,667 GRT were lost to their mines. In 1943 their kills in the area consisted of one destroyer escort, five patrol boats, one LCT, and seven merchant ships totaling 17,979 GRT; and in 1944 they sank a destroyer, two destroyer escorts, four LSTs, three LCTs, one MGB, three patrol boats, two tugs, and eleven merchant vessels of 18,004 GRT. They achieved less in the Mediterranean, where they sank with torpedoes or mines three destroyers, two destroyer escorts, one MTB, one ML, and two patrol boats. The operations in northern Norway, the Baltic, and the Black Sea were not very successful either. Seventy-seven S-boats survived the war, and 147 were lost.
The remaining heavy units were transferred to northern Norway to protect Narvik and to act against Murmansk convoys. The battlefleet had shrunk to two units after Gneisenau received a bomb hit into the forward powder magazine at Kiel before she could be sent to Norway. She was never repaired. A first sortie by Tirpitz with destroyers against convoy PQ12 in March 1942 was unsuccessful as she did not find the enemy, but she escaped an attack by torpedo planes undamaged. In the next operation against PQ17 in July 1942, Tirpitz, Admiral Hipper, and Admiral Scheer were recalled after being sighted. However, the British command panicked and scattered the convoy, allowing aircraft and U-boats to inflict heavy losses.
For the next battle in December 1942, the cruisers Admiral Hipper and Lützow and their escorting destroyers were used to attack convoy JB57b. The action was fought in very low visibility. Admiral Hipper was damaged and Lützow was ordered to retreat just as she started to attack the convoy because of instructions to avoid risk. Hitler had put high hopes on the operation and was deeply disappointed by the outcome. He ordered the immediate decommissioning of the battleships and cruisers. Admiral Raeder resigned and Admiral Dönitz was appointed as his successor.
Dönitz was clever enough to gain Hitler’s reluctent consent to keep the heavy ships commissioned a few weeks later. He argued that it was still possible to operate against Arctic convoys by being more aggressive and accepting some risk. But a year later, in December 1943, after Scharnhorst sortied to attack a convoy, she was sunk by Duke of York, cruisers, and destroyers. She had run a high risk. Heavy ship operations were over for the Kriegsmarine. Tirpitz stayed in Norway until she was sunk by air attack in November 1944; the cruisers were used as training ships in the Baltic. They lent fire support to the retreating German army before being sunk by air attacks in the last days of the war. Only Prinz Eugen, Nürnberg, and Leipzig survived.
The navy’s last great operation was the epic transportation of one and a half million civilians and half a million soldiers from East Prussia to the west. It was the greatest maritime evacuation in history.
B. SUMMARY AND ASSESSMENT
The Kriegsmarine entered war unprepared and helplessly inferior to the British and French navies. In spite of that, it began the struggle actively—unlike the Hochseeflotte in the First World War. In the war’s first years Admiral Raeder laid more emphasis on capital ships, and he resigned when this strategy ended. Admiral Dönitz pushed the submarine war but did not receive Hitler’s full support. The leaders of the Kriegsmarine never realized that Hitler’s aims were continental. He wanted Russia and her resources. In his concept, the Kriegsmarine only served to keep Britain at bay.
Under these circumstances, the Kriegsmarine performed comparatively well. With its weak means, it sank about as many ships as it lost (see tables 2.6 and 2.7).
TABLE 2.6 Allied Losses Caused by German Forces
TABLE 2.7 German Losses Caused by Allied Forces
a German battleships include an old one by mine or coast artillery.
b Allied cruisers sunk include two coast defense by surface ships and one monitor by aircraft. German cruisers include an old one by surface ships, an old one by aircraft, and two gunboats by aircraft.
A look at the merchant war against Britain shows that the submarines were the main threat (see table 2.8). U-boats conducted more than 3,400 combat patrols during the war and 648 were lost at sea in frontline operations. In comparison, Allied merchant ships made more than 300,000 successful Atlantic voyages and 100,000 more in British coastal waters.
The problems with U-boat warfare had many causes: The German submarine campaign arose from Germany’s limited options for waging war against Britain in 1939. The military failed to topple Britain’s homeland position by air attack or invasion, and the excellent results achieved in the initial submarine actions led to overoptimistic expectations. U-boats were an effective weapon as long as their technical and tactical superiority was unimpaired by Allied tactics and countermeasures (radar, direction finding, escort carriers, and so forth). The U-boat building program was trapped between the demand for high production figures and the need for technical improvements. The numerical inferiority of the German U-boat arm compared with Allied ASW forces increased greatly toward the end of war. Even at the height of the U-boat campaign in May 1943, only 236 boats with approximately twelve thousand men were available for frontline service, equaling the personnel strength of a single army division. Expectations of victory under these circumstances were unrealistic. The U-boat campaign lacked substantial cooperation from other services in the Wehrmacht, especially the Luftwaffe. The notorious German limitations in personnel and resources reduced chances for victory in a lengthy campaign to starve out Britain, which was based mainly on wishful thinking in naval staff circles, not on reliable economic and logistic analysis of the enemy situation. The operational staff of U-boat Command, which consisted of former U-boat officers promoted to staff positions, lacked external scientific advice and the operational research skills needed to improve combat effectiveness and tactics.
TABLE 2.8 Allied Merchant Ships Sunk in World War II
Quick numerical expansion of the U-boat arm during 1941–1942 and the high casualty rate thereafter resulted in a constant decline in combat experience and professional skill on the part of the U-boat crews, which negatively affected operational efficiency and loss rate. In the end, the Kriegsmarine lost a war it had not wanted and fought until the end in a hopelessly inferior situation.
