COSSAC recognized that it could not reverse the process; that is, the Allies would not be able to attack the Pas-de-Calais and mount a dummy operation aimed at Calvados that would be believable. If the attack came ashore at Pas-de-Calais, the Germans would not keep troops in lower Normandy for fear of their being cut off. Instead, they would bring their forces from lower Normandy to Pas-de-Calais and into the battle. But they might be persuaded to keep troops in the Pas-de-Calais following a landing on the Calvados coast, as the men and tanks in the Pas-de-Calais would still stand between the Allied forces and Germany. In short, geography would help to pin down the German armor in the Pas-de-Calais.
• •
To reinforce the German need to keep their panzer armies northeast of the Seine, COSSAC proposed (and Eisenhower, after he took command, mounted) an elaborate deception plan. The code name was Fortitude; the objectives were to fool Hitler and his generals into thinking that the attack was coming where it was not, and into believing that the real thing was a feint. Each objective required convincing the Germans that the Allied invasion force was about twice as powerful as it actually was.
Fortitude was a joint venture, with British and American teams working together. It made full use of the Double Cross System, of Ultra, of dummy armies, fake radio traffic, and elaborate security precautions. Fortitude had many elements designed to make the Germans think the attack might come on the Biscay coast or in the Marseilles region or even in the Balkans. The most important parts were Fortitude North, which set up Norway as a target (the site of Hitler’s U-boat bases, essential to his only remaining offensive operations and thus an area he was extremely sensitive about), and Fortitude South, with the Pas-de-Calais as the target.
To get the Germans to look toward Norway, the Allies first had to convince them that they had enough resources for a diversion or secondary attack. This was doubly difficult because of the acute shortage of landing craft—right up to D-Day it was touch and go as to whether there would be enough craft to carry six divisions ashore at Normandy as planned. Therefore, the Allies had to create fictitious divisions and landing craft on a grand scale. This was done chiefly with the Double Cross System, the talents of the American and British movie industries, and radio signals.
The British Fourth Army, for example, stationed in Scotland and scheduled to invade Norway in mid-July, existed only on the airwaves. Early in 1944 some two dozen overage British officers went to northernmost Scotland, where they spent the next months exchanging radio messages. They filled the air with an exact duplicate of the wireless traffic that accompanies the assembly of a real army, communicating in low-level and thus easily broken cipher. Together the messages created an impression of corps and division headquarters scattered all across Scotland.
Of course the messages could not read “We will invade Norway in mid-May.” The Germans would never believe such an obvious subterfuge. Instead, they read “80 Div. request 1,800 pairs of crampons, 1,800 pairs of ski bindings,” or “7 Corps requests the promised demonstrators in the Bilgeri method of climbing rock faces,” or “2 Corps Car Company requires handbooks on engine functioning in low temperatures and high altitudes.” There was no 80th Division, no VII Corps, no II Corps Car Company, but the Germans did not know that and they would come to their own conclusion as to what was going on in Scotland.6
Fooling the Germans was not easy; they were experts at radio deception. At the beginning of 1942 they had mounted one of the more elaborate and successful deception operations of World War II, Operation Kreml. Its objective had been to make the Red Army think that the main German offensive for 1942 would take place on the Moscow front, not at Stalingrad. As historian Earl Ziemke writes, Kreml “was a paper operation, an out-and-out deception, but it had the substance to make it a masterpiece of that highly speculative form of military art.” The Germans used radio traffic to manufacture dummy armies that supposedly threatened Moscow; in most of its essentials, Kreml was similar to Fortitude.7
Thanks to the Double Cross System, however, the Allies had one advantage over Kreml. The turned German spies in the United Kingdom, whose reliability had been “proved” to the Abwehr over the past three years, were put to work. They sent encoded radio messages to the Abwehr in Hamburg describing heavy train traffic in Scotland, new division patches seen on the streets of Edinburgh, and rumors among the troops about going to Norway. In addition, wooden twin-engine “bombers” began to appear on Scottish airfields. British commandos made some raids on the coast of Norway, pinpointing radar sites, picking up soil samples, in general trying to look like a preinvasion force.
The payoff was spectacular. By late spring, Hitler had thirteen army divisions in Norway (along with 90,000 naval and 60,000 Luftwaffe personnel). These were hardly high-quality troops, but still they could have filled in the trenches along the Atlantic Wall in France. In late May, Rommel persuaded Hitler to move five infantry divisions from Norway to France. They had started to load up and move out when the Abwehr passed on to Hitler another set of “intercepted” messages about the threat to Norway. He canceled the movement order. To paraphrase Churchill, never in the history of warfare have so many been immobilized by so few.8
Fortitude South was larger and more elaborate. It was based on the First U.S. Army Group (FUSAG), stationed in and around Dover and threatening the Pas-de-Calais. It included radio traffic, inadequately camouflaged dummy landing craft in the ports of Ramsgate, Dover, and Hastings, fields full of papier-mâché and rubber tanks, and the full use of the Double Cross System. The spies reported intense activity around Dover, including construction, troop movements, increased train traffic, and the like. They said that the phony oil dock at Dover, built by stagehands from the film industries, was open and operating.
The capstone to Fortitude South was Eisenhower’s selection of Lt. Gen. George S. Patton to command FUSAG. The Germans thought Patton the best commander in the Allied camp and expected him to lead the assault. Eisenhower, who was saving Patton for the exploitation phase of the coming campaign, used Patton’s reputation and visibility to strengthen Fortitude South. The spies reported his arrival in England and his movements. So did the British papers (available to the Germans in a day or two via Portugal and Spain; in addition, German agents in Dublin had the London papers the day they were printed and could send on hot items by radio). FUSAG radio signals told the Germans of Patton’s comings and goings and showed that he had taken a firm grip on his new command.
FUSAG contained real as well as notional divisions, corps, and armies. The FUSAG order of battle included the U.S. Third Army, which was real but still mostly in the States; the British Fourth Army, which was imaginary; and the Canadian First Army, which was real and based in England. There were, in addition, supposedly fifty follow-up divisions in the United States, organized as the U.S. Fourteenth Army—which was notional—awaiting shipment to the Pas-de-Calais after FUSAG established its beachhead. Many of the divisions in the Fourteenth Army were real and were actually assigned to Bradley’s U.S. First Army in southwest England.
Fortitude’s success was measured by the German estimate of Allied strength. By the end of May, the Germans believed that the Allied force included eighty-nine divisions, when in fact the number was forty-seven. The Germans thought the Allies had sufficient landing craft to bring twenty divisions ashore in the first wave, when they would be lucky to manage six. Partly because they credited the Allies with so much strength, partly because it made good military sense, the Germans believed that the real invasion would be preceded or followed by diversionary attacks and feints.9
• •
It was more important for the Germans not to know that Calvados was the site than it was for them to think that the Pas-de-Calais (and Norway) was. “The success or failure of coming operations depends upon whether the enemy can obtain advance information of an accurate nature,” Eisenhower declared in a February 23, 1944, memorandum.10
To ensure security, the Allies went to great lengths. In February, Eisenhower asked Churchill to ban all visitor traffic to the coastal areas in southern England, where the base for the attack was being built and where training exercises were under way, for fear that there might be an undiscovered spy among the visitors. Churchill said no—he could not go so far in upsetting people’s lives. General Morgan growled that Churchill’s response was “all politics” and warned, “If we fail, there won’t be any more politics.”11
Still the British government would not act. But when Montgomery said he wanted visitors banned from his training areas, Eisenhower sent an eloquent plea to the War Cabinet. He warned that it “would go hard with our consciences if we were to feel, in later years, that by neglecting any security precaution we had compromised the success of these vital operations or needlessly squandered men’s lives.” Churchill gave in. Visitors were banned.12
Eisenhower also persuaded a reluctant War Cabinet to impose a ban on privileged diplomatic communications from the United Kingdom. Eisenhower said he regarded the diplomatic pouches as “the gravest risk to the security of our operations and to the lives of our sailors, soldiers, and airmen.”13 When the government imposed the ban, on April 17 (it did not apply to the United States or the Soviet Union), foreign governments protested vigorously. This gave Hitler a useful clue to the timing of Overlord. He remarked in early May that “the English have taken measures that they can sustain for only six to eight weeks.”14
With the British government cooperating so admirably, Eisenhower could not do less. In April, Maj. Gen. Henry Miller, chief supply officer of the U.S. Ninth Air Force and a West Point classmate of Eisenhower’s, went to a cocktail party at Claridge’s Hotel. He began talking freely, complaining about his difficulties in getting supplies but adding that his problems would end after D-Day, which he declared would be before June 15. When challenged on the date, he offered to take bets. Eisenhower learned of the indiscretion the next morning and acted immediately. He ordered Miller reduced to his permanent rank of colonel and sent him back to the States—the ultimate disgrace for a career soldier. Miller protested. Eisenhower insisted, and back he went. Miller retired shortly thereafter.15
There was another flap in May when a U.S. Navy officer got drunk at a party and revealed details of impending operations, including areas, lift, strength, and dates. Eisenhower wrote Marshall, “I get so angry at the occurrence of such needless and additional hazards that I could cheerfully shoot the offender myself. This following so closely upon the Miller case is almost enough to give one the shakes.” That officer too was sent back to the States.16
• •
To check on how well Fortitude and security were working, SHAEF relied on Ultra intercepts. Each week the British Joint Intelligence Committee issued a summary of “German Appreciation of Allied Intentions in the West,” one- or two-page overviews of where, when, and in what strength the Germans expected the attack. Week after week, the summaries gave SHAEF exactly the news it hoped to receive: that the Germans were anticipating an attack on Norway, diversions in the south of France, Normandy, and the Bay of Biscay, and the main assault, with twenty or more divisions, against the Pas-de-Calais.
The Germans poured more concrete to make more fortifications in the Pas-de-Calais than anywhere else. They stationed more troops there, backed up by the panzer divisions. They concentrated their mines in the Channel off the coast of the Pas-de-Calais. They grossly exaggerated the resources available to SHAEF. They were, in short, badly fooled.
But not completely. The mobility the AEF enjoyed thanks to command of the sea and air forced the Germans to regard almost any suitable beach as a possible invasion site. At a March 19 conference at Berchtesgaden, Hitler put the problem to his senior commanders: “Obviously an Anglo-American invasion in the west is going to come. Just how and where nobody knows, and it isn’t possible to speculate.” But speculate he did, as the German ability to penetrate Fortitude was nonexistent and their ability to penetrate the AEF’s security measures was limited. A few reconnaissance planes did get through; they did spot the buildup of shipping in the southern ports of Southampton and Portsmouth; but as Hitler pointed out, such intelligence was almost useless. “You can’t take shipping concentrations at face value for some kind of clue that their choice has fallen on any particular sector of our long western front from Norway down to the Bay of Biscay,” he said, because “such concentrations can always be moved or transferred at any time, under cover of bad visibility, and they will obviously be used to dupe us.”
That did not stop him from guessing; indeed, he had to guess. “The most suitable landing areas, and hence those that are in most danger, are the two west coast peninsulas of Cherbourg and Brest: they offer very tempting possibilities. . . .”17 It was a bad guess.
Adm. Theodor Krancke, commanding Navy Group West, guessed that the invasion would come between Boulogne and Cherbourg, either in the Cotentin or at the mouth of the Orne, the mouth of the Seine, or the mouth of the Somme, which was a little better—but as Boulogne to Cherbourg included most of the Kanalküste, hardly pinpoint accuracy.18
Rommel’s guess was the Pas-de-Calais. He spent more of his time there than anywhere else on his long front, inspecting, prodding, building defenses. At the beginning of May he began to look slightly to the southwest, telling Lt. Gen. Gerhard von Schwerin, commanding the crack 116th Panzer Division of the Fifteenth Army, “We expect the invasion on either side of the Somme estuary.”19
But all the evidence available to the Germans continued to indicate the Pas-de-Calais. The pattern of AEF air activity, for example, reinforced Fortitude. There were twice as many AEF reconnaissance flights over Fifteenth Army’s sector as there were over Seventh Army’s; there were almost ten times as many air raids on targets northeast of the Seine as in lower Normandy. So Rommel continued to look to the Pas-de-Calais. He was confident that if the AEF invaded there, he could defeat the assault.
On April 27, German Schnellbootes (abbreviated S-Boote and called E-boats by the Allies for “enemy boat”) penetrated an Allied shipping concentration for a practice exercise—code name Tiger—and sank two LSTs. For the AEF the loss of more than 700 men was a major blow; for the Germans, the information that the Allies were practicing at Slapton Sands, on the south coast of England, was potentially useful. Hitler saw this at once. Although he had never been to England, or to the Cotentin or Calvados, he had the most amazing ability to store topographical information in his mind. In this instance, he noticed the similarity between Slapton Sands and the Cotentin beach (which was why the AEF was carrying out practice exercises at Slapton Sands) and began to insist strongly on the need to reinforce the defense in lower Normandy.20
Within the severe limits in which the Wehrmacht in the West was required to operate, this was done. On May 29, the weekly AEF intelligence summary included a chilling sentence: “The recent trend of movement of German land forces towards the Cherbourg area tends to support the view that the Le Havre-Cherbourg area is regarded as a likely, and perhaps even the main, point of assault.”21 Had the Germans penetrated the secret of Overlord? Only the event would tell; meanwhile, the good news was that the main panzer forces remained northeast of the Seine, with Fifteenth Army.
• •
When? Morgan’s directive declared “as soon as possible.” March was out. Even if the AEF got a couple of good days to cross and land, the probability of a spring storm smashing against the Calvados coast during the establishment and buildup phase made March too risky. April 1, the target date suggested by the U.S. Joint Chiefs of Staff (JCS), was no good because of uncertain and unpredictable Channel weather and because the spring thaw in Russia would make it impossible for the Red Army to launch a coordinated offensive. Morgan therefore picked May 1. When Eisenhower took command, he moved the target date back to June 1, in order to have the use of an extra month’s production of LSTs, LCVPs, and other landing craft.