9

 

North Africa: A Pendulum Swung by Codebreakers

 

 

During the war in North Africa, Allied and Axis forces continually pursued each other back and forth over harsh desert sands, losing vast numbers of men in the process. Many factors could be cited for the swings of fortune, but close study shows that none had more impact than signals intelligence. When the Axis was breaking Allied codes, they were the winners. When the Allies sealed their informational leaks and gained cryptologic superiority, they in turn were triumphant.

Rommel's early victories certainly owed much to the unconventional generalship and unexpected moves in the midst of combat that earned him renown as "the Desert Fox." What was not known at the time was that he also gained a powerful advantage through two secret sources. One was a field cryptographic team that expertly listened in on enemy radio exchanges to inform Rommel of British tactical plans. The other was the American military attaché in Cairo, who was kept informed of British strategic decisions and, all unknowingly, passed them on to Rommel.

Captain Alfred Seeböhm led the mobile unit that stayed close to the front lines and tuned in to British wireless traffic. His intercept operators sopped up every bit of undecoded chat and every message transmitted in a field code the Germans were readily breaking. Seeböhm added to his intelligence haul by using call signs to identify British units, and direction finding to ascertain troop concentrations and movements.

One example illustrates the use Rommel made of this information. On the morning of June 16, 1942, when Rommel was driving to isolate Tobruk, Seeböhm's team overheard a radiotelephone conversation between the Twenty-ninth Indian Brigade and the Seventh Armored Division. It disclosed that the garrison at the strongpoint of El Adem intended to launch an attack that night. Rommel responded by ordering his Ninetieth Light Division to strike first. The British, surprised, had to surrender. The larger import was that with the capture of El Adem, Rommel was able to surround and isolate Tobruk, which had been a thorn in his side for months. He soon forced the Tobruk garrison to capitulate, handing over enormous stores badly needed by the Afrika Korps. The surrender also delivered to the world press another disheartening story of British failure.

The U.S. Cairo-based military attaché was Colonel Bonner Frank Fellers. He became Rommel's unwitting dupe because of the code he used. America's Black code, so called because of the color of its binding, had been surreptitiously copied by the Italian secret service and made available to the Germans. As America's chief military observer in Egypt, Fellers was like Japan's Baron Oshima, an energetic gadabout and a tireless reporter. The British were obliging to him because they hoped he would aid them in securing much-needed lend-lease equipment for the desert forces. He himself felt driven to help prepare the American military for desert warfare. He toured the battlefields, talked with commanders, studied their tactics, was often made privy to their plans and then spilled all that he had collected in long, meticulous dispatches that he dutifully enciphered in the Black code and radioed off to Washington—and to Rommel.

Reading Fellers's reports makes one's skin crawl in horror. Through him Rommel turned unexpectant British garrisons into sitting ducks ready to be pounced on by the Desert Fox. Of course, Fellers's giveaways were only a turnabout of what Allied decrypts were routinely doing to unexpectant Axis garrisons. But somehow the sheer nakedness of his disclosures and the awfulness of their consequences are especially penetrating.

For example, he told of forthcoming commando raids by the British, which the Germans met and destroyed. He described defects the Allies had discovered in Axis armor and aircraft, and thereby facilitated corrections that made the equipment more killingly effective. He supplied a complete rundown on where the British armored and motorized units were located at the front, how many tanks were in working order and how many had been damaged. He tipped Rommel off to the withdrawal of 270 airplanes and a quantity of antiaircraft artillery to reinforce British strength in the Far East. He reported the locations of the air squadrons and how many of their planes were operational.

Fellers's revelations played a key role in another of the North African war's reversals. After his earlier successes against Wavell, Rommel had been hurled back by the British under General Claude Auchinleck at the end of 1941. But by receiving what Gordon Welchman called "just about the most perfect intelligence any general could wish for," Rommel knew exactly when and where to strike in his counteroffensive of January 1942. He made the British retreat three hundred miles, and destroyed or captured thousands of men in the course of the campaign.

Rommel might well have gone on to Cairo except for one obstacle: his tanks ran out of gas. The failure underlined the importance of the island of Malta, lying midway between Sicily and the Axis bases in North Africa. The supply shortages that hindered Rommel were a direct result of the depredations on Axis convoys carried out by Malta-based planes, ships and submarines. All-out bombing by German and Italian aircraft could not subdue the island, nor could the German commander in Italy persuade Hitler to commit the land forces to conquer it. Fellers handed the Axis an opportunity, if not to put Malta completely out of business, then at least to greatly hamper its raids on shipping.

The island, too, had its supply problems, and in June 1942 the British planned to have convoys converge simultaneously on Malta, one from the east, the other from the west, as the means of preventing the Axis from directing all its might against either one. To further neutralize Axis attempts to attack the convoys, the British planned to bomb the Italian warships, destroy Axis planes on the ground and air-drop commandos in Italy to sabotage other airfields. All of this Fellers learned about in advance and dutifully reported.

The result was a massacre. The Germans and Italians shot the descending parachutists, stood off the attacks on the airfields and sent ships, submarines and planes against the convoys. Britain's losses included a cruiser, three destroyers and two merchant ships. The convoy from Alexandria was forced to turn back. Of seventeen ships, only two got through to Malta, crippling for a time the island's effectiveness in sinking Rommel's supply ships.

At this low point the cryptologic pendulum again swung to the Allies. British cryptanalysts stopped the exploitation of Fellers by the simple expedient of breaking the Black code, reading his dispatches and putting two and two together. Convinced that the British suspicions were true, the American command recalled Fellers. He resumed his earlier service with MacArthur and became a brigadier general on Mac's staff. The new attaché to Cairo was equipped with a Sigaba code machine. Rommel lost his best informant and his strategic advantage.

Around the same time he was also deprived of his tactical weapon. Amid the desert ebb and flow the British launched an armored thrust that overran the staff headquarters of the Afrika Korps. Seeböhm was killed, his men mostly wiped out or captured and many of the unit's records seized. An added asset from the strike was the surrender of a very cooperative German officer, Seeböhm's second-in-command. This lieutenant's admissions concerning the poor radio practices of British operators guided the tightening of their cryptographic disciplines. Plus, the Germans' new field unit proved very much inferior to Seeböhm and his team.

From then on, Allied cryptology in North Africa never again lost its leading edge. Rommel was shown to be much less prescient in his decision making. Or as Welchman expressed it, "Much of the foxiness of the 'Desert Fox' was due to German radio intelligence."

 

 

First El Alamein: Long-Delayed Turning Point

 

Despite being outclassed, for a time, by the Seeböhm-Fellers decrypts, British cryptologists were steadily strengthening the flow of intelligence they were supplying to North African commanders. Early on, GC&CS decrypts kept General Wavell well informed about Rommel's posting to North Africa and about the forces under his command. Yet these authoritative disclosures could not offset command blunders.

Wavell thought the newly arrived Rommel would behave as he himself would have in the German general's situation. That is, he would delay any serious action until he was firmly in place and all of his equipment had arrived. Wavell was confirmed in these expectations by dispatches from Rommel's superiors in Berlin specifying that in view of the limited supplies of men and materiel they could send him, he should assume only a defensive position in North Africa.

That was not Rommel's way of thinking. He believed in boldness, speed, surprise. Knowing from Fellers's decrypts that Wavell's forces had been depleted by the need to send troops to Greece, Rommel decided that, ready or not, he should strike. He quickly organized what he had in men and machines, built fake tanks mounted on Volkswagens to create the impression he had more armor than he did, and went on the offensive. There were no messages to warn of his attack. Caught off guard, the British reeled back, giving up to the newly energized German-Italian assault troops most of the territories O'Connor had won. As Rommel wrote triumphantly to his wife, "I took the risk against all orders and instructions because the opportunity seemed favorable."

If Rommel, in that early stage of his North African adventures, could have captured Tobruk as an entry port for convoys from Italy, he might well have driven on into Egypt. When the Tobruk garrison held out, the overextension of his supply lines, especially for gasoline, forced him to bring his campaign to a halt.

While Wavell has been judged by analysts to have been an able commander, his attempts to recoup his losses against Rommel were doomed by rigidities in his and his subordinate generals' attitudes toward combat. One such shortcoming was their refusal to accept the tank-killing power of the Germans' 88-millimeter gun. Although this heavy weapon had been developed for antiaircraft use, the Germans had learned in the Spanish civil war that when its barrel was lowered and leveled against tanks, it could blast through the enemy's best armor. British commanders kept sending unescorted tanks against it and seeing them brew up into blazing hulks. The British had an antiaircraft gun whose penetrating power was greater than the 88's, but using it against anything other than aircraft was something one just didn't do.

Accompanying this failure was the generals' reluctance to break down the walls of interservice rivalries. Rommel excelled in combined operations, in which infantry supported tanks, artillery and antiaircraft units worked together and Luftwaffe planes were closely coordinated with ground forces. These tactics the British commanders were slow to adopt. Their units moved into battle splendidly independent of one another—and the Germans picked them to pieces.

So it was with Wavell's next big offensive, code-named Battleaxe. His multiple responsibilities as commander in chief of the entire Middle East kept him tethered in Cairo while his subordinate generals carried out his Battleaxe plans. They were no match for Rommel. Wavell came forward at the last minute to take control, but it was too late. His carefully amassed infantry battalions and armor had been shattered. The best he could do was keep the defeat from turning into a rout that would deliver Egypt into Rommel's hands.      

In historians' eyes, Winston Churchill shared the onus for catastrophes in North Africa. Avid for victories that could strengthen world opinion about Britain's power to fight, and armed with BP decrypts that informed him of reinforcements headed for the Afrika Korps, he coerced his commanders into attacking before they were ready. Then, when the offensive stumbled, he peremptorily sacked his commander in chief and replaced him with another.

Having failed, in Churchill's estimation, to "save our situation in Egypt from the wreck" of Greece and Crete, Wavell was transferred to a less demanding post in India. Claude Auchinleck took over in Cairo. Although the Auk, too, was considered a sound leader, he had one crucial failing. He was a poor judge in choosing his frontline generals, and he was slow to remove them even when their deficiencies were glaring.

He withstood Churchill's impatience and reorganized what now became known as the Eighth Army. Freed from the threat of invasion as Hitler focused on his Russian offensive, Britain was pouring men, guns, armor and planes into North Africa in numbers that exceeded those going to the Afrika Korps. Auchinleck's field general, Alan Cunningham, should have had the edge when he attacked Rommel. But he made the same mistakes of sending his unescorted tanks against entrenched 88s and allowing infantry, armor, artillery and aircraft units to act too autonomously. The result was another disaster. The strain of command reduced Cunningham to a nervous wreck; he had to be relieved and sent to recuperate at a Cairo hospital. Auchinleck, like Wavell, hurried to the front, took over, held off another Rommel surge into Egypt and forced him to retreat—a narrow standoff victory for the Eighth Army.

The Auk did little better in his next choice of command, Neil Ritchie. In January 1942, when Rommel counterattacked and confronted Ritchie with the myriad decisions of combat, the new general went "all haywire," as one of his subordinates put it. Auchinleck flew in to stabilize the situation and stave off the Germans, but he left Ritchie in place.

The war settled into stalemate as each side prepared for new initiatives. It was the kind of seemingly stagnant situation Churchill couldn't abide. Relying strictly on the numbers of men and armor delivered to Auchinleck, he determined that the Eighth Army had a comfortable superiority that justitled an early offensive. What the prime minister overlooked was the operational capability of those numbers. Although the British were receiving a steady inflow of American-made Grant tanks that were more than a match for most of Rommel's armor, the machines had to be prepared for desert warfare, and the crews trained in their use. Similarly, the new infusions of troops and armor from distant comers of the Commonwealth had to be organized and trained. The Auk was diligently handling these preparations when he received Churchill's ultimatum: either attack by June or resign.

Ultra decrypts, however, told Auchinleck that the issue was to be taken out of his hands. Rommel had decided to attack late in May. Auchinleck advised Ritchie of two points where Rommel was most likely to strike and insisted that Ritchie position his two divisions of armor at those points. Ritchie ignored the advice. When Rommel drove forward, the British armor was dispersed, ready to be destroyed one unit at a time. When Ritchie tried to counterattack with what was left of his tanks, he sent them, unescorted, to be smashed by the 88s.

This time Rommel even took Tobruk—at the embarrassing moment when Churchill was meeting with Franklin Roosevelt and trying to convince FDR that Britain was not a lost cause.

Rushing forward once again, Auchinleck withdrew his battered army to Matruh. When the Afrika Korps also took that strongpoint, Rommel wrote to his wife, "We're already 60 miles to the east. Less than 100 miles to Alexandria." All that stood in his way were the remnants of the Eighth, which Auchinleck was reorganizing at El Alamein. Rommel stopped for twenty-four hours to prepare his next attack.

Auchinleck, however, did the better preparing. He studied the Ultra decrypts and learned where Rommel would strike. Dispensing with interservice noncooperation, he faced the Desert Fox with his own version of a combined force. When Rommel, having to operate with little benefit from signals intelligence, grouped his tanks for a frontal strike, he was met by Auchinleck's massed artillery. Knowing that his adversary was starving for reinforcements of German troops and having to depend on Italian divisions, the Auk chose the Italian sector for his counterattack. His coordinated infantry and armor fell on the Italians and routed them.

Correlli Barnett, historian and author of The Desert Generals, has claimed that July 2, 1942, was the pivotal moment of the war in North Africa. On that day Auchinleck stopped Rommel, and on the days following he forced the German to change from an offensive into a defensive frame of mind. In the First Battle of El Alamein, Auchinleck turned back the last great Nazi thrust to conquer Egypt.

For Churchill, however, the Auk's effort was too little too late. He sacked Auchinleck and brought in Harold Alexander to be his Middle East chief of staff. Bernard Montgomery became the new commander of the Eighth Army.

 

 

Monty: Sigint Helps Make a Hero

 

Assigned to take over in North Africa in mid-August 1942, Alexander and Montgomery benefited from impeccable timing. Allied strength in the theater was on a mighty upsurge while Rommel's was in swift decline.

By then, U.S. war production had shifted into high gear. The supply of Grant tanks to Egypt was being supplemented by the arrival of thirty-six-ton but swift-moving Shermans whose 75-millimeter guns were, unlike the fixed weapons of the Grants, mounted on power-driven turrets. Britain was pouring reinforcements into the Eighth Army. By the time Montgomery was ready to go on the offensive, he had almost a two-to-one superiority over Rommel in men, tanks, antitank guns and artillery. In the air, the Royal Air Force was dominant over the Luftwaffe. Nor did Montgomery have any lack of gasoline to power his vast machine.

Monty profited from another tremendous advantage: Bletchley Park was breaking the ciphers Rommel most depended on. Four days after Montgomery took command, the complete details of Rommel's order of battle were handed to him. In his Memoirs, published well before the Ultra secrets were made public, Monty made much of his "intuition" for directing the winning moves in combat, intimating that his genius alone had crushed Rommel in North Africa. His chief intelligence officer's reply was, "Montgomery won his first battle by believing the intelligence with which he was furnished."

Montgomery's critics also point out that he exaggerated the poor state of affairs in the desert before he took over. His picture of the Eighth Army under Auchinleck was one of incompetence and ruin. He told Churchill, and repeated in his autobiography, the untruth that the Auk was ready to give up El Alamein and retreat to the delta if Rommel launched another attack in strength.

The more accurate description is that Auchinleck bequeathed to him a veteran staff settling down after their first defeat of Rommel to develop plans for a new attack. Their ideas formed the basis for Montgomery's self-touted "Master Plan."

Monty's many detractors, though, can't deny that he was a leader who inspired confidence and respect in his men. Dressed casually in a pullover sweater and the medallion-decorated beret that became his trademark, he went into the front lines to have tea with his troops, give them pep talks and exude a sense of sureness that the Goddess of Victory, not to mention the God in heaven, were on his side. His intelligence officer Edgar Williams's reaction after hearing Monty's first address to his headquarters staff was, "Thank God this chap has got a grip." Staffer William Mather told Monty's biographer Nigel Hamilton in an interview, "Monty absolutely deserves all the credit he could get for the way he changed us. I mean, we were different people. We suddenly had a spring in our step."

British codebreakers were doing him another service. Daily they were breaking some two thousand Hagelin-encoded Italian messages, many of them relating to shipments to Rommel. Decrypts of German air force and Fish signals were rising toward ninety thousand a month. All of these inside glimpses, put together, were providing so complete a picture of Axis shipping plans that Britain's Mediterranean forces were able to pick and choose which transports would go through—those with supplies for British POWs, for example—and which ones, especially the tankers carrying gasoline to Rommel, would be sunk. As Monty was preparing his El Alamein offensive, the Royal Navy and Air Force were sinking more than forty-five percent of the shipping meant to supply the Afrika Korps.

The British were careful, in carrying out this ravaging of the Axis marine, to preserve the security of Ultra. When decrypts specified the course of an Axis transport, an RAF reconnaissance plane would take off from Malta and seem, as merely part of a routine patrol, to happen upon the vessel. Meanwhile, a Malta-based submarine or bomber would already be on its way to intercept the ship. As Hinsley recalled the results in a 1996 reminiscence, "The Germans and the Italians assumed that we had 400 submarines whereas we had 25. And they assumed that we had a huge reconnaissance airforce on Malta, whereas we had three aeroplanes!"

A man with the sharp intelligence of Albert Kesselring, Hitler's commander in chief in Italy, was suspicious of the "extraordinary losses incurred during sea transport." He "suspected that the times of our convoy sailings were betrayed." But instead of questioning broken codes, he blamed the sinkings on "the efficiency and wide ramifications of the enemy system of sabotage."

The results for Rommel were catastrophic. He faced the Eighth Army short of ammunition, with rations for his troops at a low level, and so deprived of gasoline that he was robbed of freedom of movement. As he commented in The Rommel Papers, which his wife and son put together after his death, "The battle is fought and decided by the Quartermasters before the shooting begins." He leaves no doubt that with adequate supplies, including a sufficient tonnage of gasoline, he could still have defeated an enemy that was "operating with astonishing hesitancy and caution." As it was, El Alamein became, as he entitled one of his chapters, the "Battle Without Hope."

Added to his troubles was his vulnerability to the sort of deception he had earlier used against the British. Wanting Rommel to believe Eighth Army forces were being built up in the south, Montgomery ordered the creation of dummy battalions, with fake tanks, bogus artillery and troop simulations that went so far as to have balloon soldiers sitting on inflatable latrines. A masterstroke was a mock water pipeline made up of discarded gasoline cans. It was left unfinished to fool the Germans into believing the attack would not come until the line was completed.

Rommel, a sick man, lulled by Monty's trickery, had actually returned to Germany for treatment when the Eighth Army struck. His second-in-command, fat General Georg Stumme, trying to cope with the complexities of combat, died of a heart attack. Healthy or not, Rommel flew back to resume command.

Montgomery's critics can't deny that he divined the most likely point of Rommel's attack: the Alam al-Halfa ridge. He prepared to meet and destroy Rommel's armor there. Four days after he'd made this decision, Ultra decrypts confirmed that a thrust against the ridge was exactly what Rommel intended. Monty's acute military analysis, backed by the codebreakers, gave him the victory in the defensive phase of El Alamein.

When the Eighth Army went on the offensive, however, Montgomery's Master Plan turned out to have serious flaws. Needing to break through in-depth minefields, Monty planned to have sappers clear a narrow channel through which his infantry and armored divisions would pour during the first hours of the offensive. The plan went awry when the minefields proved to be a tougher, more time-consuming problem than he'd anticipated. His infantry and armor had to wait until a defile was cleared. Then the mass of troops and tanks trying to crowd through it created confusion, causing further delays and heavy losses. He had, in effect, to throw away his Master Plan and improvise his further moves, but he did this with calm authority and, in the end, carried the day.

Rommel, his armor all but immobilized by lack of fuel, had no choice but to concentrate on evacuating his armies to avoid annihilation.

Here that "astonishing hesitancy and caution" he had observed of Montgomery came to Rommel's rescue. To the amazement and dismay of the onlookers at Bletchley Park, Montgomery made no move for three days after Rommel had started his retreat. He seemed so dazzled by his victory that he could not bring himself to order the end runs that could have trapped the exhausted, near-helpless Afrika Korps, and send them into prisoner-of-war camps. In his memoir Monty blamed heavy rains for his failure to overtake Rommel, even though the rains did not begin until after those first three days of idleness. However it was, the Afrika Korps kept ahead of belated British sorties and reached Tripoli. They were headed there at the time of Anglo-American landings in French North Africa and were available to continue the war in North Africa for four more months of brutal fighting.

 

 

The Afrika Korps: Ultra Tightens the Noose

 

In 1942, after the U.S. had joined the war, Anglo-American planners held long discussions on how to conduct joint future campaigns. The Americans argued for a cross-Channel invasion in 1943. Knowing how much preparation was needed before that attempt could be made, the British advocated that the first substantial combined operation should instead be a series of North African landings. Agreement was reached and a timetable set for the autumn of 1942, with a little-known American general, Dwight D. Eisenhower, in charge.

It was just as well that the British won the argument. The North African landings showed up countless fumbles, mix-ups and snafus that needed to be corrected before taking on the Germans in northern France.

The North African expedition was, in fact, a tissue of bungles. The primary objective was to seize the Tunisian ports of Bizerte and Tunis, to prevent the Axis from using these ports that provided the nearest and best harbors for transports from Sicily and Italy and the best exits for an evacuation. To achieve the objective, the British felt sure, the landing should be made as far east as possible, hard on the Algeria-Tunisia border. The Americans were cautious about venturing so far. All sorts of fears entered in—among them the threat that Hitler might press France and Spain into allowing German passage through to capture Gibraltar, whose fall could maroon troops east of the Rock. To forestall any such eventuality, the Americans urged at least one landing in Morocco, west of Gibraltar. With that safeguard, a Mediterranean landing could also be contemplated.

A compromise was reached. Operation Torch would be made up of three landings: at Casablanca in Morocco, and at Oran and Algiers in Algeria. After securing these sites, it was thought, Allied troops could speed across land to capture the Tunisian ports.

The trouble was that even the easternmost landing, in Algiers, was still 450 miles from Tunis. They were tough miles, much of the way through rugged mountain terrain. As canny Scots general Kenneth Anderson noted, the race for Tunis was lost before it began.

The November 8, 1942, landings came just four days after Rommel's defeat at El Alamein. In themselves they represented a magnificent achievement. An armada of some five hundred American and British ships had set out from ports as far apart as Portland, Maine, and Lock Ewe, Scotland, and had converged on North Africa without ever being touched by German U-boats. GC&CS decrypts showed that Axis leaders knew something big was afoot, but the messages also disclosed uncertainty about the destination. Italy, Sardinia, Sicily, Malta, the Aegean? The Axis commanders' most favored answer, as Ultra made clear, was that this was a convoy bound for the relief of Malta. The Allies used that information to carry off a bit of deception. The Mediterranean ships made a feint as though heading for Malta, then wheeled about and sailed for Algiers. The Axis commanders were fooled, and the landings were a surprise.

Aside from the Allies' own foul-ups, the landings went off more smoothly than anticipated. Only at Algiers did the French troops, supposedly loyal to the Vichy regime, show troublesome resistance. The Axis Mediterranean submarines managed only two attacks and damaged one ship. The German and Italian air forces were caught unprepared and did little to harass the landings. Neither France nor Spain acceded to a German march on Gibraltar.

One big problem remained: Tunis and Bizerte were objectives too far. Algerian roads were in poor condition. Railroad equipment was ancient and the tracks were of mixed gauges. The intended harelike dash was slowed to a tortoise crawl.

In addition, the planners seriously misjudged the Axis response. With Rommel beaten and the Russian offensive demanding close attention, the Allies doubted that Hitler would try another major gamble in North Africa. Even if he did, they believed, the preparations would take weeks. They were wrong on both counts. Hitler saw the danger in allowing the enemy to gain possession of the ports providing the best jumping-off point for an invasion of Sicily and Italy. The troops, armor and planes that Rommel had pleaded for and been denied now flowed in great numbers and with stunning speed into Tunisia. The capable, aggressive General Jürgen von Arnim was called back from the Russian front to share command with Rommel.

The Allies' push to reach the ports foundered. In addition to the surprising resistance by the Germans, winter rains turned roads into quagmires. Eisenhower called off the offensive, and both sides settled down to a winter spent gathering their strength. The race for Tunis had, indeed, been lost.

By the time the Allies resumed their drive into Tunisia, their intelligence advantage had become even more overwhelming. With mastery of Luftwaffe traffic a routine matter, BP cryptanalysts were also penetrating Wehrmacht Enigma ciphers. They had broken a new Enigma key that provided a fresh font of knowledge about Axis shipping. Italy's air force book code and Hagelin-encoded navy cipher were being quickly read. And Magic decrypts of Baron Oshima's reports continued to be helpful.

Axis commanders, by contrast, were reduced to guesses and hunches. An example of what this disadvantage could mean in battle came when Rommel—with his Afrika Korps troops safely dug in at the Mareth Line of old French fortifications in Tripoli—hurried west to join Arnim in organizing attacks against the Allies trying to hold the passes in the Atlas Mountains. Rommel's panzers succeeded in overpowering the untried American troops in the Kasserine Pass and fanned out into the plain beyond. He could have placed the whole North African operation in jeopardy if he had kept his drive going. But he had to guess at what lay ahead, and his guess was that the Allies were readying a counterattack that could trap him. Although his guess was wrong, he had no means of dispelling the uncharacteristic sense of caution that overcame him. When an American artillery division was hastily brought forward and began lobbing mortar shells onto Rommel's armor, he called off the offensive and withdrew through the pass. What was perhaps the greatest Axis opportunity in the campaign withdrew with him.

The battle for Tunisia was a series of gory thrusts and counterthrusts that continued through March and April and into May 1943. The code-breakers influenced the outcome in two critical ways. One was by keeping the Allied commanders informed about virtually every major action their Axis counterparts planned to take. The other was by directing the stranglehold on Axis supply lines.

Ultra's effects on strategic operations are exemplified by a March 3 decrypt that Hinsley described as of "decisive importance." It alerted Montgomery that Rommel, back with his old Afrika Korps troops, was organizing a surprise breakout from the Mareth Line against the Eighth Army on March 6. In a hard-driven day-and-night frenzy of activity, Monty used the three days to quadruple the forces in place at the point Rommel meant to strike. An in-depth massing of 470 antitank guns and 400 tanks was camouflaged to blast the Germans as they came forward. Rommel wrote later, "It became obvious that the British were prepared for us." After his attack had failed, the Desert Fox went home to Germany. This time he did not return.

Once more the Germans suspected that Enigma had been compromised. The British high command rebuked Montgomery for not making a greater effort to disguise the source of his intelligence. But again the suspicions were quelled, and use of the Enigma never wavered.

U.S. general Omar Bradley told, in his A General's Life, how the code-breakers helped the American soldiery regain a measure of respect from their British allies after the near rout of the GIs at Kasserine Pass. Arnim planned, on March 23, a counterattack against the U.S. II Corps at El Guettar. "Our front-line codebreakers," Bradley wrote, "picked up and decoded the order, giving us a full day's notice. . . . A second decoded message provided us further valuable details on the attack." So warned, the Americans "mauled the Germans and Italians . . . it was the first solid, indisputable defeat we inflicted on the German Army in the war. Kasserine Pass had now been avenged."

As for the Axis supply situation, Ultra decrypts made the clampdown by the Allies all but total. Arnim's armored divisions, like those of Rommel before him, were immobilized by lack of fuel. Many of his soldiers were soon existing on two slices of bread per man per day.

Without transports and control of the sea, Axis commanders could not manage a Dunkirk. When resistance ended and Arnim surrendered on May 13, Hitler and Mussolini had no choice but to abandon 275,000 German and Italian soldiers and all their equipment.

From Tunis, Alexander sent a message to Churchill: "Sir, it is my duty to report that the Tunisian campaign is over. All enemy resistance has ceased. We are masters of-the North African shore."

So ended an error-filled campaign that had resulted in more than one hundred thousand men—Germans, Italians, Britons, Americans, French—being killed, wounded or missing in action. As Rommel colorfully phrased it, "Rivers of blood were poured out over miserable strips of land which, in normal times, not even the poorest Arab would have bothered his head about."

But the campaign opened the underbelly of Europe to Allied attack, and it welded the Allied forces into a strong, unified and confident team. From the perspective of the codebreakers, the greatest significance was that the campaign proved to Allied generals the value of trusting their intelligence sources.