Codebreakers Victory (38 page)

Decrypts had also shown that the Marshalls' defenders lacked the aircraft to mount a full-scale surveillance of their perimeter and were consequently focusing their searches on the most likely approaches from the south and southeast. Nimitz directed his U.S. Navy task force to drive in from the unguarded northeast. As a result, conquest of Kwajalein and its neighboring atolls in early February 1944 went forward in an orderly fashion, with a third of the casualties suffered at Tarawa. The taking of Eniwetok, farther west in the Marshalls, was more savagely contested by another suicidal Japanese defense, but it, too, fell in five days and was secured by February 21.

Meanwhile, in the southwest Pacific, MacArthur had cleaned the Japanese out of New Guinea except for guerrillas hiding and starving in the hills and had seized the islands of Wakde and Biak, off the big island's northwest coast.

Originally the Nimitz-MacArthur pincer movement was meant to close in on the Japanese stronghold of Rabaul. Now they no longer saw the need to spend lives battling the hundred thousand Japanese troops stationed there. Rabaul could be reduced by bombing and naval firepower and left to wither on the vine. The more northerly fortress at Truk was similarly pounded into a smoking ruin and bypassed.

With all of this favorable news unfolding, MacArthur could look northward with lip-smacking anticipation: his next move would land him on Philippine soil.

 

 

Massacre of the Marus

 

Studying the reports on the war in the Pacific, one can't help but wonder how the Japanese failed to conclude that their codes were being broken. This wonderment pertains especially to the movements of Japanese transport vessels, the marus trying to shift troops or bring supplies to Japanese outposts and meet the import needs of the Japanese nation. Having broken JN-11, the "maru code," the codebreakers time and again foretold when Japanese ships were scheduled to leave port, the planned course of their voyages, their stops for refueling and their expected times of arrival at their destinations. And time after time the marus were intercepted by Allied ships, submarines or planes and destroyed. The decrypts became so numerous that the informants no longer concocted cover stories as to how else the information might have been obtained. They simply sent out a message and let the Allied attackers follow up on it, confident that the Japanese would never lose faith in the inviolability of their codes.

Allied submarines, in particular, showed up wherever Japanese ships went. The accepted explanation seemed to be that the Allies had so many subs they simply blanketed the Pacific with them. A Japanese prisoner reported that in Singapore it was a common saying that one could walk from that port to Japan on American periscopes. The reality was summed up in Jasper Holmes's memoir: "There were nights when nearly every American submarine on patrol in the Central Pacific was working on the basis of instructions derived from cryptanalysis."

Historian John Winton has determined from official sources that while submarines constituted only two percent of the American war effort in the Pacific, they sank two-thirds of the total merchant-ship tonnage and one out of every three Japanese warships sent to the bottom.

American subs achieved these results despite having to rely on torpedoes that, for nearly the first two years after Pearl Harbor, often proved defective. They had two main flaws: their guidance systems frequently caused them to go too deep and pass under their targets, and even when they hit, their faulty detonators failed to make them explode. Submarine captains often heard their torpedoes thump against the sides of the enemy vessels without going off. Ordnance officials continued to claim that the trouble lay with the captains: they were incompetent; they couldn't aim properly. But the contrary evidence mounted, bolstered by codebreakers' receipts of Japanese messages reporting such incidents as ships arriving in harbor with unexploded torpedoes embedded in their flanks. New designs finally corrected the flaws, and the submariners' scores improved.

The Japanese were indefatigable reporters. They not only supplied the Allies with full information about their shipping schedules; they also aired their losses. The codebreakers were, consequently, able to confirm the results of Allied raids.

In the last months of 1943 and throughout 1944 the sinkings reached incredible rates. In November 1943, a total of 120 decrypts were transmitted to the submarines, with another 40 messages adding to or correcting the originals. These guided the subs in sinking 43 ships, of 285,820 tons, and damaging another 22 vessels, of 143,323 tons, making a total of 429,143 tons in one 30-day period. In December a U.S. sub scored the first Allied sinking of an aircraft carrier.

During 1944 the sinkings reached their peak. No less than 548 vessels totaling 2,451,914 tons, went down. So many tankers were sunk that fuel became a desperate problem. The subs sank a converted ferry, gunboats, a cruiser. Trying to reinforce threatened island garrisons by transferring troops from Taiwan and Manchuria, the Japanese had many transports sunk, with heavy losses of soldiers adding to those of the sailors.

While at the outset of the war the submarine strength of the Imperial Navy roughly equaled that of the U.S. Navy in the Pacific, the Japanese made ineffectual use of their subs. One important reason was that their submarine crews disdained attacking merchant vessels; they were at war to take on warships. The result was that they never tried to cut off the supply lines from the U.S. to Australia. As the war proceeded, the Japanese began more and more to use their subs in all sorts of tasks, such as carrying supplies, that might better have been left to other types of vessels. The subs became so ineffective a threat to Allied shipping that the U.S. soon stopped bothering with convoys and began sending out transports unescorted.

As 1945 began, the rate of sinking by Allied submarines declined, for one significant reason: they simply ran out of targets. Their stranglehold on the Imperial war machine and the Japanese economy was all but complete.

The postwar tribute penned by U.S. Vice Admiral Charles Lockwood included a compliment that, though a bit backhanded, says it all: "During periods, which fortunately were brief, when enemy code changes temporarily cut off the supply of Communication Intelligence, its absence was keenly felt. The curve of enemy contacts and of consequent sinkings almost exactly paralleled the curve of Communication Intelligence available."

 

 

 

15

 

France: Invasions from North and South

 

 

At their Quebec conference, in August 1943, Eisenhower and his Joint Chiefs had decided that their cross-Channel invasion would fall on the Caen section of the Normandy coast, and had set a target date of May 1, 1944. As they settled into their final planning for the offensive, one of their most reliable information sources was their inadvertent spy on the continent, Baron Hiroshi Oshima. Nazi generals continued to handle "Hitler's Japanese confidant" with kid gloves. As part of his treatment, Lieutenant General Günther Blumentritt, chief of staff under Rundstedt, gave him a thorough briefing on German defenses from the Netherlands to the French Mediterranean coast, a report that included the order of battle for all German armies engaged in coastal defense.

Oshima went to see for himself. He toured the fortifications and learned firsthand how the Germans had aligned themselves along the coast and what divisions they held in reserve. His military attache, Colonel Seiichi Ito, accompanied the baron to record his own observations.

All this exposure to German plans the Japanese wrote up in lengthy reports that they transmitted to Tokyo, using the Purple machine. The reports were, of course, before Allied eyes as quickly as the baron's superiors in Japan saw them. As one U.S. translator later noted, "In the end we produced a pamphlet, an on-the-ground description of the North French defenses of 'Festung Europa,' composed
dictu mirabile [sic]
by a general."

Armed with reliable information from their codebreakers, Allied commanders could plan with confidence. Historical accounts of the Normandy landings written in the years soon after war's end gave them a mythic quality of bloody and heroic but never-in-doubt triumphs. Only decades later has it become clear what a near miss the gamble was and how much its success depended on the massive deception program that was an integral part of the Allies' plans. While the overall code name for this great series of hoaxes was Operation Bodyguard, that main part of it relating to the Normandy invasion went by the code name Fortitude. What has also been made evident is how much the outcome of Fortitude depended on signals intelligence. Without this superstructure of inspired fakery, and the intelligence to know that it was succeeding, the best guess is that the Normandy invasion either would not have been tried at that time or would have been driven back into the sea.

The Germans in their planning were not merely lacking reliable input. The eyes they trusted to inform them about the situation in Britain were those of double agents relaying skillfully slanted misinformation. The conditions were ripe for the most ingenious bit of military artifice since the Trojan horse.

The Allies were aided by German preconceptions. If the situation had been reversed and the invasion left up to the German generals, there would have been no hesitation as to where the blow would have fallen: on that northern jut of French coast called the Pas de Calais. It was, after all, the planned jump-off point for their invasion of Britain in 1940. The Germans could argue, persuasively, that it narrowed the Channel crossing to just twenty miles and was easier to defend from the air. In addition, landings in this easternmost sector offered the most direct route to the Rhine and the German heartland. The high command were so convinced by their reasoning that, as BP decrypts made clear, they positioned the entire highly mechanized, veteran Fifteenth Army in the Pas de Calais as a key element of Army Group B, which Erwin Rommel had been called upon to lead as a subordinate to the commander in charge of West Wall defenses, Field Marshal Gerd von Rundstedt. The commanders also believed that landings anywhere else would be only diversions preceding the main attack.

Hitler himself feared every possible eventuality. As General Blumentritt told Liddell Hart after the war, "Hitler was constantly on the jump—at one moment he expected an invasion in Norway, at another moment in Holland, then near the Somme, or Normandy and Brittany, in Portugal, in Spain, in the Adriatic. His eyes were hopping all around the map."

Lacking reliable information, the German commanders felt obliged to be ready to fend off the full range of possibilities. The navy admirals felt sure the landings would come near Le Havre, since the Allies would need a large port. The Nazi generals could make a case for an attack in all the places Hitler worried about and some others besides. Hitler confided to Oshima, whose report was decrypted by Magic, that while invasion across the Channel was the most effective action the Allies could take, they might judge it too hazardous and decide to land in the less heavily defended areas around Bordeaux or perhaps in Portugal. As D-Day approached, although the Germans' focus narrowed to the north coast of France, and Hitler came to believe that at least the first phase of the attack would come in Normandy, they could never be sure. They continued to hold divisions in place to counter all of these potential landing sites.

This was precisely what the Allied tricksters wanted Fortitude to accomplish: to scatter German divisions in as many places as possible other than Normandy and hold them there even after the landings were made. They also sought to fool the Germans as to the timing of the invasion, to convince them it couldn't possibly come before July.

To carry out the varied deceptions it was necessary to create ersatz armies. At the spy-training camp he had established in Canada, William Stephenson had his "Magic Group," headed by well-known British magician Jasper Maskelyne. The group had become expert in fashioning dummy tanks and guns, trick air bases, false fleets of landing craft and other impedimenta of war. With its aid the British put into place in Scotland their Fourth Army, which the Germans believed to be an expeditionary force of 250,000 men assembling for an attack on Norway. In actuality, the "army" consisted of 28 overage officers and 334 enlisted men. The army's radio operators used a British invention that enabled one operator to simulate the traffic of entire networks. The delusion was strengthened by British special units mounting a series of raids against industrial and military installations in Norway, as though scouting the way for the larger force. Also, Allied planes stepped up reconnaissance over the fjords. Because of all this activity, twenty-seven divisions in Scandinavia stayed put to withstand the Fourth Army's coming assault.

An even more ambitious stroke of Fortitude artifice was the creation of the First U.S. Army Group (FUSAG) in southeastern England opposite the Pas de Calais. FUSAG had several real fighting units and a real commander: George Patton, released from punitive limbo, making himself highly obvious in the area with his pearl-handled pistols, his pampered bulldog mascot and his intemperate spoutings-off to the press. But the group's main forces were nonexistent; the army was fake. Aerial recon by Axis planes found the fields filling with tanks and guns. The pilots spotted tracks off into the woods suggesting that even more armor was hidden there—the tracks had been made at night by real tanks. German scouts looked down on field hospitals, kitchens, troop encampments, oil docks and clusters of landing craft—most of which were concoctions of canvas, plywood, papier mache and inflated rubber. Postwar, German general Alfred Jodl recalled that fifteen divisions had been held in the Pas de Calais, ready to turn back landings that never came.

In the Middle East another semifictional army was spawned. As with FUSAG, the British Twelfth Army, based in Egypt, included both real and imaginary elements. Its role, so the Germans were led to believe, was to launch a drive through Crete and Greece at the same time that the Russians attacked from the north. Again, augmented reconnaissance flights and air attacks as well as a buildup of bogus landing craft to be seen by German recon planes lent credence to the hoax. The Germans shifted additional troops to the Balkans to hold off that invasion.