Codebreakers Victory (37 page)

Edward Drea's
MacArthur's Ultra
summed up the Hollandia offensive as the codebreakers' "single greatest contribution to The General's Pacific strategy." Drea also saw it as a masterpiece of integrating signals intelligence "into operational planning to deceive, outmaneuver, and isolate an opponent."

By this one daring leapfrog of an attack, MacArthur had extended his control to halfway along New Guinea's fifteen-hundred-mile northern coast—and a lot farther toward his goal of stepping again on Philippine soil.

Perhaps the most telling commentary on MacArthur's tactics was that given after the war by Japanese intelligence officer Colonel Matsuichi Juro. He called The General's envelopment techniques "the type of strategy we hated most." Juro described how, repeatedly, MacArthur, "with minimal losses, attacked a relatively weak area, constructed airfields and then proceeded to cut the supply lines. . . . Our strong points were gradually starved out. . . . The Americans flowed into our weaker points and submerged us, just as water seeks the weakest entry to sink the ship. We respected this type of strategy . . . because it gained the most while losing the least."

While these land and air battles were proceeding satisfactorily, the Allied and Imperial navies were battering each other in a series of engagements. Although in these battles the Japanese generally sank more ships than they lost, the factor of fleet attrition was coming to the fore. The fighting in the South Pacific claimed far more warships, especially destroyers, than Japan's production could replace, while American shipyards were sending veritable armadas of new vessels down the ways. Also, Yamamoto had expended much of the cream of Japan's experienced fliers in ill-advised attacks, many of which were tipped off by Allied codebreakers, against strongly fortified targets. Well-trained airmen were another resource Japan was not replenishing.

It was in these waters that John F. Kennedy, skippering patrol torpedo boat
PT-109,
had his close call with early death. Patrolling off the Solomons on August 2, 1943, Kennedy had his boat rammed, split in half and set afire by a Japanese destroyer. Two of the crew of thirteen were killed outright and a third was badly burned. Towing the injured man by clenching the ties of his life jacket in his teeth, Kennedy led the others on a four-hour swim to Plum Pudding Island, well within the Japanese area of control. Fortunately the destruction of
PT-109
had been sighted by a coast watcher. After six days of hiding out and of desperate recon swims by Kennedy, who had been on the Harvard swim team, the eleven survivors were found by natives who were pro-Allies, and a rendezvous was arranged with another torpedo boat. Kennedy's life was spared probably by the impotence of Japanese cryptanalysts. The codes used by the coast watcher in reporting the loss of his boat and arranging his crew's rescue were ones that even a moderately skilled analyst should have solved. But only Allied receivers read the messages, and the rescue operation went off without interference.

 

 

Codebreakers Plot Yamamoto's Fall

 

One of the most thankless but necessary tasks of intelligence units was the deflation of exaggerated battle reports. Allied codebreakers could set the records straight, but Admiral Yamamoto had no comparable service to correct his fliers' overoptimism. His spirit was buoyed, therefore, by the inflated claims of success by his aviators in their series of raids meant to blunt any planned offensive the Allies might try after Guadalcanal. The admiral came south to Rabaul to begin a tour in which he would review operations and encourage his men. Allied cryptanalysts intercepted messages that offered a tempting possibility: Yamamoto's itinerary would bring him within range of planes lifting off from Henderson Field. Since Yamamoto was known to pride himself on his punctuality, he and his retinue could be expected to follow a precise schedule. Did the Americans dare an aerial ambush?

It was a vexing question. Japanese confidence in their code systems still held. But if American planes suddenly appeared in the correct time and place to intercept Yamamoto's tour—wouldn't that convince the most diehard believer that the Japanese system had been compromised?

When Admiral Nimitz was presented with the decrypts, his answer was to go for it. The removal of so venerated a leader would count for far more than the possible jeopardy to this one phase of Allied codebreaking. Besides, the coast watchers provided a viable cover story: personnel involved in the mission, and thus vulnerable to capture, would be told that the information came from informants at Rabaul. Nimitz secured the approval of the higher-ups in Washington.

On the morning of April 18, 1943, a flight of sixteen fighters took off from Henderson Field and flew at wave-top height to sneak under radar detection and avoid sightings by pro-Japanese coastal watchers. The American timing had to be precise. Even with drop tanks, the four-hundred-mile distance to the point of interception was at the far edge of the P-38s' limits; they couldn't wait around for Yamamoto and his escorts to appear.

There was no need to worry. The two Mitsubishi bombers bearing the admiral and members of his staff, along with protecting Zeros, were right on time. Part of the American flight soared up to take on the Zeros and provide cover. The other planes slipped in, raked the bombers with fire and sent the one bearing Yamamoto flaming into the jungle.

The admiral's death had the desired effect. When it was belatedly reported to the public in May, the Japanese people were profoundly shocked. Many later traced their disheartenment with the war to that moment. Yamamoto, always a dangerous offensive force, was replaced by a conservative, defense-minded strategist.

As David Kahn summed up the episode, "Cryptanalysis had given America the equivalent of a major victory."

 

 

Nimitz Goes Island-Hopping

 

While MacArthur was making end runs up the long coast of New Guinea, Chester Nimitz was intent on forcing the Japanese to contract the perimeter of their Greater East Asia Coprosperity Sphere.

He was having to plan without the services of Joe Rochefort. In the autumn of 1942 the credit war claimed Rochefort as victim. His superiors in Washington, regarding him as a prickly obstacle in the way of their earning plaudits for major intelligence coups, continued to be incensed that he had made fools of them in their off-the-mark predictions. In October he received orders to report for temporary duty at the Office of Naval Operations in Washington. His staff thought this would be good for him. He would gain a respite from the hard work and bad air-conditioning at Pearl Harbor that had given him a persistent bronchial cough and caused him to lose a lot of weight. He might, in transit, get to spend a few days with his family in California. He might even be given a decoration or promotion.

Rochefort knew better. Benefits were not what Washington had in mind. By then Naval Intelligence had been taken over by Admiral Joseph R. Redman, who had eased out Laurance Safford, OP-20-G chief and a good friend of Rochefort. In Safford's place, Redman had installed his younger brother, John. For Admiral Redman, a primary personal objective was to gain control over the intelligence network of the U.S. Navy. As Rochefort said in his reminiscences, Redman wanted "to have somebody on Hypo that would be a creature of his, and this obviously was not going to be Rochefort." Turning over to Jasper Holmes a package of personal papers and the keys to his desk, Rochefort predicted to his doubting colleagues that he would not return to Pearl Harbor.

His assertion was quickly verified when he reached Washington. He was accused of "squabbling" with Nimitz's staff members, opposing a recent reorganization and failing to keep his headquarters informed. After a brief stay in Washington, he was eventually assigned to the Tiburon peninsula in California, where he served as an instructor in the Floating Drydock Training Center. With Rochefort out of the way, the Redman brothers wrote their own history that claimed Midway as an OP-20-G triumph and gave Rochefort only the briefest, most grudging mention.

So mean-spirited were they that when Nimitz recommended Rochefort to receive the Distinguished Service Medal, they saw to it that the award was blocked. In 1958, when Nimitz tried again, he was told that the time had passed for awarding medals in recognition of World War II service. It was not true: Rochefort was granted the medal. The only trouble was that by that time he had been dead for nine years.

The Navy's chief of staff, Admiral Ernest J. King, did salvage some of Rochefort's intelligence skills and knowledge. In late 1944 he recalled Rochefort to join a special group preparing intelligence summaries for him. But Rochefort's time in the Floating Drydock Training Center was a long year lost to Allied intelligence—and what a mockery of an assignment it was for the man responsible, in the words of his associate Holmes, for "the greatest intelligence achievement in the Navy's history."

Meanwhile, late in March 1943, Hypo's codebreakers warned Nimitz that a Japanese convoy was being sent to reinforce the troops holding the Aleutian islands of Attu and Kiska. Nimitz organized a task force to intercept. In an inconclusive sea battle, the Americans succeeded in turning back the reinforcements only because the Japanese vice admiral, at the critical moment when his way was actually clear to make the landings, chickened out and withdrew—and was summarily relieved of his command.

During May, Nimitz assigned an infantry division to retake Attu. The conquest cost the Americans more than five hundred lives, but of the Japanese garrison of twenty-five hundred men only twenty-eight survived after one last banzai sake-soaked suicidal charge. When the U.S. troops moved on to attack Kiska, they found that under the cover of an impenetrable Aleutian fog the Japanese had evacuated their entire force. The northern arc of Japan's defense ring no longer extended to American shores.

In Nimitz's island-hopping campaign across the central Pacific, his targets were much different from MacArthur's. The General most often plotted his course over large land masses—New Guinea is approximately the same in land area as Alaska. The great coastal distances gave him opportunities for his clever triphibious operations. Nimitz, on the contrary, faced clusters of tiny atolls, mere pinpricks of land in the vast reaches of the Pacific. His formula for success had to be quite different: send in ships and planes to bombard the immediate island as near to rubble as possible; then dispatch troops in landing craft headed for the beaches and cover their approach with air, bombardment and naval gunnery. MacArthur complained to the chiefs of staff about the enormous losses of lives resulting from Nimitz's tactics, but one wonders whether he could have managed a real alternative or was just undercutting a rival commander. This much is true: when The General did have to take a small island, such as Biak, off the northwestern end of New Guinea, he used a frontal attack, ran into fanatical dug-in Japanese resistance and suffered a considerable number of casualties.

On November 20, 1943, Nimitz launched the first of nine atoll landings he would make in his approach to the Philippines. His objective: atolls in the Gilbert Islands, most particularly Makin and Tarawa. These bits of sand and coral, on the outer edges of Japan's defense perimeter, Nimitz regarded as threats that must be eliminated before he moved on to more important seizures in the Marshall Islands.

The Americans faced unprecedented challenges in conducting this kind of atoll warfare, and their first try was a disaster. Even though signals intelligence identified the Japanese units and determined their numbers almost to a man, the Sigint advantage could not offset the botched execution of the invasions. The opening aerial and naval bombardments, which seemed annihilating to the officers involved, actually did little to weaken the defenders, holed up in caves and tunnels or protected by parapets of concrete and palm logs. The bombardments were not well coordinated, leaving lapses that allowed the Japanese soldiers to recover and reestablish themselves. Confusions and snafus in the landing operations exposed men needlessly to Japanese fire.

Makin, now named Butaritari, was known to be only lightly garrisoned and was expected to fall in hours. Instead, its die-rather-than-surrender Japanese held out so stubbornly that only in the third day could the U.S. field commander radio, "Makin taken." The delay gave a Japanese submarine time to sneak in and sink, with heavy loss of life, an aircraft escort carrier that would long since have withdrawn if the battle ashore had gone more swiftly.

The horrors of Tarawa shocked the nation. U.S. Marines descended on the main island of Tarawa's ring of atolls expecting to find the enemy dead or dazed by the fierce prelanding bombardment. Instead they encountered Japanese gunners zeroed in to blast many of the landing craft out of the water. Because of bad forecasts, the invasion fleet headed for the beaches at the time of an exceptionally low tide, with the result that the landing craft hung up on hidden reefs. The Marines had to wade in thigh-deep water for more than a hundred yards under devastating fire. The remnants of the main force who made it ashore had to fight for the island inch by inch, using hand grenades and flamethrowers to subdue the defenders. The battle went on for a murderous seventy-six hours. Photos of dead Marines sinking facedown in Tarawa sand brought to the American public a fresh awareness of what victory in the Pacific war would entail.

Tarawa was a hard learning experience. By the time Nimitz was ready to invade the Marshalls, he made sure more accurate data foretold water levels and tide changes. Teams of frogmen went in with demolition charges to clear away barriers. Improved landing craft were designed and rushed to the Pacific. Scores of other improvements included more destructive bombardment patterns, better disembarkation procedures, stronger ground-to-air radio liaison and new methods to subdue Japanese strongholds.

Nimitz, as ever, based his decisions for the Marshalls strike on what his codebreakers were telling him. Decrypts confirmed that the Japanese were expecting the attacks to fall on the outer rim of atolls and in this expectation were shifting troops out of centrally located Kwajalein to these peripheral outposts. Nimitz's decision to land on Kwajalein startled his staff as well as the Japanese.