by John Prados
“We’ve hit the jackpot!” Lasswell exclaimed.
Red Lasswell remembers, “I personally did the whole thing overnight.” Having been a key participant on the Midway decrypts, Lasswell contributed to possibly the two greatest radio intelligence achievements of the Pacific war. “I didn’t feel, somehow or other, the joy in this [the Yamamoto decrypt] that I did in the other, because I sort of felt more of a snooper,” Lasswell remembered. He was glad he did not have to make the call. Lieutenant Donald M. Showers plotted the itinerary and checked times and distances on maps to verify plausibility.
The same thing happened in Washington. At Negat, Lieutenant Commander Prescott Currier had the predawn watch when the intercept arrived. He took it to the “Blitz Additive Room.” In the morning, code maven Commander Redfield “Rosie” Mason practically skipped through the office, yelling at everyone to double-check everything. He assigned linguists Phillip Cate, Dorothy Edgars, and Fred Woodrough to make the translation. Rosie Mason, whose private passion was Greek and Roman mythology, was hard to please, but decided the result was “good”—high praise. A touch of spring hung in the air and the weather was mild, recalled linguist Edward Van Der Rhoer, on watch when the final version appeared. It stunned Van Der Rhoer, who read it with growing excitement, realizing that the intelligence was “actionable”—it offered the opportunity to kill Yamamoto Isoroku. Such a death would rise to the Olympian heights of Rosie Mason’s favored mythological tales.
Both units put their versions of the decrypt on Copek on April 14. Pearl Harbor was out of the starting gate a bit faster—about an hour and a half. FRUMEL contributed a decrypt of another message between Japanese subordinate commands—possibly one of the dispatches Admiral Joshima had worried about. OP-20-G reported the result to Admiral King and Navy Secretary Knox. At CINCPAC Red Lasswell and Jake Holmes took the message file to Eddie Layton.
The fleet intelligence officer immediately realized the importance of this message and carried it to Nimitz. Captain Layton met with Admiral Nimitz shortly after 8:00 a.m. Nimitz asked whether Layton thought it worthwhile to take a shot at the enemy commander, and the latter responded that Yamamoto’s death would shock Japan. Nimitz worried that the enemy might be able to bring in a better commander, but when they discussed the possibilities—Nimitz was surprisingly well acquainted with the enemy’s senior officer corps—they agreed the Imperial Navy had no one better than Yamamoto. Another consideration was the danger that such action would confirm to the Japanese their codes had been breached. Admiral Nimitz decided to proceed, then wrote a cable to SOPAC commander Halsey ordering him to try the ambush. This chronology is confirmed in the CINCPAC war diary for April 14, which records that Yamamoto would inspect Buin four days hence, arriving from Rabaul by plane—and on April 16 the diary notes, “[A]n attempt will be made to intercept an enemy high commander when he makes a projected visit to the Buin area the 18th.”
Because several authors, including Nimitz biographer E. B. Potter, have written that this move was cleared with President Roosevelt and Secretary Knox due to Yamamoto’s stature, the question of approval is worth comment. This writing is very shortly after the May 2011 U.S. commando raid into Pakistan to kill the terrorist leader Osama bin Laden, personally ordered by President Barack Obama. The Yamamoto ambush is an obvious parallel. Roger Pineau spent decades attempting to determine whether FDR made an affirmative decision on Yamamoto. Pineau came up empty. This writer walked the same path with a similar result. There is no evidence in Roosevelt’s papers, the records of COMINCH, CINCPAC, or the National Security Agency; and, in fact, the president was traveling during this period and out of touch. Nimitz’s cables were routinely copied to King and Knox for information, and in the records there are no answering messages on April 14 or 15 that comment on the Yamamoto kill order either pro or con. Certain books have printed quotations of an alleged message from Secretary Knox, but this appears to have been fabricated. The SOPAC mission planner recalls seeing a cable from Knox, but the document has never materialized and the timing given suggests it may have been an exhortation to the field forces, not an execute message. There seems little reason to doubt that Nimitz, at his own level, made the decision to get Yamamoto, and higher authority did not impede him. The world was simpler then.
Be that as it may, it was up to Admiral William F. Halsey’s South Pacific forces to do the deed. A few argued for hitting Yamamoto’s boat en route to one or another inspection site, but he might survive a boat sinking more easily than an air crash. Halsey convened his aviation specialists, including his new air boss, Rear Admiral Marc A. Mitscher, who had arrived just days before. It happened that April 18, the day of the trip, was the anniversary of the Doolittle Raid, and Mitscher wanted to do something special. The ambush, soon called the “Y-Mission,” seemed just the thing. Marine Major John P. Condon, the AIRSOLS fighter staff officer, planned the operation starting on April 17. Condon decided that Army twin-engine P-38 fighters, if given extra fuel tanks, could fly to Bougainville with enough gas to afford them time for the interception. The 339th Fighter Squadron, the “Sun Setters,” got the assignment.
Under Major John Mitchell, then the leading ace on Guadalcanal, the force consisted of a covering unit of fourteen P-38s, and an attack unit of four planes led by Captain Thomas G. Lanphier Jr. Mitchell distrusted the compasses in the Lightning aircraft, important because Condon had planned an indirect approach, taking a route west of New Georgia until heading northeast, then north to make Bougainville. Condon found Mitchell a nautical compass, eliminating the problem. Mitchell chose the intercept point; then Condon calculated the necessary parameters. Dissatisfied with Condon’s planned course, Mitchell recalculated it. Departure from Fighter Two was timed precisely to bring Lanphier to the intercept point just as Admiral Yamamoto’s planes reached there. Mitchell’s group would fly very low—as low as ten to thirty feet altitude—to avoid detection by Japanese radars.
Palm Sunday, April 18, dawned clear and humid. Mitchell’s planes took off at 7:25 a.m. One of Lanphier’s attack group blew a tire on takeoff and another found its extra fuel tanks were not feeding properly. Those aircraft returned to base. Thus sixteen P-38s winged toward Bougainville.
At Rabaul/Vunakanau, Captain Konishi Yukie of the 705th Air Group selected two of his best pilots to fly the Bettys that would carry Admiral Yamamoto’s traveling party. For security reasons the crews were not told until after bedtime. They were shaken awake and given detailed instructions. Petty Officer Hayashi Hiroshi thought this just a routine mission until Konishi warned him to wear full uniform. He had been used to utility gear. Hayashi was told they would fly to Buin—not Ballale, as the Americans had decoded—and that bothered him, since he had never landed there. The six Zero pilots of the 204th Air Group at Lakunai, also carefully selected, had a similar experience. Captain Sugimoto Ushie, however, informed his fliers the previous afternoon. The escort might not be strong but they were good men. Petty Officer Hidaka Yoshimi was an ace with twenty victories. The Bettys would shuttle over to Lakunai, closer to Yamamoto’s billet; then the entire sky train would leave from there.
Admiral Yamamoto’s group assembled for an 8:00 a.m. departure. At the last moment senior air staff officer Commander Toibana Yurio convinced Watanabe to give up his place. Though Toibana’s assistant was already going, the air officer was anxious to speak to frontline aviators. Commander Watanabe had a myriad of matters to take care of before the fleet staff returned to Truk. So Toibana flew on Yamamoto’s airplane. In an eerie twist of fate—perhaps exacting retribution—it had been Toibana, in China in 1937, who had been a key figure in the Panay incident, convincing superiors to delay word to their attack planes that an American gunboat cruised in their strike area.
Vice Admiral Ugaki recorded that the songbirds were pleasant that morning. He and Yamamoto left Governor’s Hill ten minutes before plane time. Toibana, his deputy, and others came from the direction of the control tower. Ugaki was puzzled to discover two officers i
n dress whites when he had decreed field uniforms, but they turned out to be the fleet surgeon and paymaster. One would fly in each airplane. The men boarded. Yamamoto’s Betty took off first, then Ugaki’s. Petty Officer Hayashi piloted the aircraft carrying Admiral Ugaki. The fighters formed up over Lakunai. A V of three stationed itself above and to the side of each transport. Hayashi kept such tight formation with the lead plane, Ugaki remembers, that he feared their wingtips might touch and cause an accident. The flight plan, designed to enable Yamamoto to see something of the war theater, took them to the southern tip of New Ireland, then along the eastern coast of Bougainville. The Bettys descended to lower altitude for optimal viewing. The route took them over the bases at Buka and Kieta, turning inland to head toward Buin. The planes rose to about 6,500 feet.
Admiral Ugaki had just been handed a note telling him to expect landing in fifteen minutes when lightning struck. Major Mitchell’s P-38s came from below. Warrant Officer Yanagiya Kenji, flying one of the escort, about 2,000 feet above the Bettys, looked down and saw them under attack. The Japanese fighters were surprised, because Allied fighters most often dived from above. Before they could intervene, the Bettys were already embattled. Major Mitchell’s covering Lightnings interposed. Captain Lanphier and Lieutenant Rex Barber made the crucial gun runs. While the American pilots have disputed credit for the success, what matters is that both Bettys were smoked and both crashed, Yamamoto’s in the jungle and Ugaki’s just off the Bougainville shore. One P-38 was lost in the clash, but the strike team returned without further incident.
No one, including Commander Toibana, survived the crash of the airplane carrying Yamamoto Isoroku. The admiral’s body would be found by Commander Watanabe, who grabbed the first plane he could get and mounted a frantic search for survivors. Pilot Hayashi, chief of staff Ugaki, and paymaster Kitamura Gen escaped from the Betty crashed in the surf. Badly injured, already sick, Admiral Ugaki spent months in the hospital.
At the daily staff meeting the next morning in Nouméa, Richmond Kelly Turner whooped it up when the shoot-down was announced. Admiral Halsey, privately exulting, chose to tease Turner. “Hold on, Kelly! What’s so good about it?” the Bull groused. “I’d hoped to lead that scoundrel up Pennsylvania Avenue in chains.”
Commander Watanabe Yasuji understandably obsessed over everything that preceded Yamamoto’s death. He discovered that his original message, supposed to have been confined to Navy radios, had in fact passed over Army circuits also. This bit of confusion created an obstacle to the Imperial Navy’s realizing its codes had been cracked. Watanabe nursed his suspicions. In 1949 Roger Pineau interviewed him on behalf of Samuel Eliot Morison. Watanabe’s one question for Pineau concerned the Yamamoto trip message and which radio net had betrayed it. Pineau, sworn to secrecy about Ultra until the codebreaking was declassified in 1978, begged off answering. Watanabe Yasuji had had a hearty reputation in the Imperial Navy as a ladies’ man. In the 1950s he—and Kusaka Jinichi also—morphed into devotees of Zen Buddhism.
The Yamamoto shoot-down had huge consequences for Japan. Nimitz and Layton had been right that the Japanese lacked admirals of his stature. Tokyo managed to keep Yamamoto’s death secret for a month. His body was cremated, Commander Watanabe accompanied the ashes to Truk, and the remains were carried home aboard fleet flagship Musashi. A state funeral was held. Yamamoto’s ashes were divided in two parts, one buried on the grounds of the Imperial Palace, the other in his hometown. But while the nation grieved, the war in the Solomons heated up to fever pitch.
THE YEAR OF THE GOAT
In the animistic, twelve-year cycle common in many Buddhist countries, 1943 was the Year of the Goat. Though the Asian image of that is different, more positive than the Western one, Japan would need to overcome adversity. In particular, since Imperial Japan’s fiscal year started with April, the death of Admiral Yamamoto was an especially bad setback at the outset of a new year of war. Aboard the Carrier Division 2 flagship Hiyo, Commander Okumiya was standing near recently promoted Vice Admiral Kakuta at Truk when the Musashi lowered her flag in honor of Yamamoto. Only a few days earlier Kakuta and Yamamoto had stood together in Rabaul. Now the C-in-C was dead. Okumiya’s heart skipped a beat when he saw the color drain from Kakuta’s face. The air officer struggled with his emotions too.
The feeling of shock was universal. Hara Tameichi arrived at Truk aboard the destroyer Shigure a week after Yamamoto’s death. Upon recuperating from his exertions off Guadalcanal, Hara had been elevated to command a full division of destroyers, though his promotion to captain had yet to come through (he gained that rank on May 1). Captain Hara went to the Musashi to report to Admiral Ugaki. Hara worried that the Imperial Navy’s repetition of formulas led to unnecessary losses, and he wanted to make this argument through Ugaki, whom he knew, to Yamamoto. Climbing the superbattleship’s Jacob’s ladder from his launch, Captain Hara found only a single warrant officer to greet him, a breach of protocol in receiving a unit commander. The whole ship seemed odd and somber, and when the captain declared that he wished to visit Admiral Ugaki, the man stared at him as if he were mad. The warrant hesitated, but finally led Captain Hara into the Musashi. “No officers were evident along our route, and the men I saw looked bewildered and depressed,” Hara later wrote. The man conducted him to Yamamoto’s cabin, which opened to wafting incense and dim light. Suddenly Hara recognized an urn of ashes on a draped table. The sailor explained, “These are the remains of our Commander-in-Chief and six of his staff officers. Admiral Ugaki and the others were critically injured.” Captain Hara teared up, and he offered a silent prayer for the dead.
Sagging morale was evident, disturbing, and could be dangerous to performance. Four of the six fighter pilots who flew escort on Yamamoto’s fated trip would be dead within months. No doubt morale worries figured among Emperor Hirohito’s reasons for visiting the Musashi on June 24, during her sojourn in the Empire after she delivered Yamamoto’s remains.
Meanwhile, the more Captain Hara learned, the more alarmed he became. Reporting to his fleet commander, Vice Admiral Kondo Nobutake, Hara discovered his division existed only in name. All his vessels except one were on loan to other units. Kondo’s haggard appearance and hoarse, slow voice also shocked Hara, who knew the admiral’s reputation as a dapper gentleman. And once Captain Hara read the files, he went from anxiety to deep gloom. Allied airpower constricted Japanese naval operations like a python snake, while Halsey’s South Pacific naval forces steadily grew, their strength presently towering over the Imperial Navy’s. The record of the Bismarck Sea battle was especially shocking. Leaving Kondo’s flagship Atago, Hara stopped at the officers’ club, where he encountered Koyanagi Tomiji, now chief of staff to Admiral Kurita. Koyanagi explained the Allied skip-bombing method. Hara quickly realized that unless the Navy could develop a counter, the jig might well be up. At Rabaul even the water was being rationed. No one had bread. Meat and vegetables went first to high-command messes, while the clever supply clerks of the base forces managed to divert much of what was left. The destroyermen got the dregs. Koyanagi had led Tanaka Raizo’s destroyer squadron, in which Hara had sailed. He trusted Koyanagi. Hara felt like a student on his first day in college.
Japanese officers might be depressed, but on the other side of the mirror Allied leaders were not quite riding high. Admiral Halsey saw the enemy redoubts at Munda and Vila becoming major thorns in SOPAC’s side. The need to retrain troops and the disagreements with MacArthur hindered Halsey’s grinding ahead. The delay attendant in preparing new Russells bases also retarded an offensive. Even as codebreakers put finishing touches on their Yamamoto shoot-down decrypts, Halsey flew to Australia to coordinate with MacArthur. It was the first time they had met, and in person they cooperated very well.
In the meantime Admiral Halsey wore the enemy down. The Imperial Navy had begun sending the Tokyo Express to its new outposts as early as February. It had also run a few merchant ships into those places. Interdicting the traffic led the Bul
l to order offensive mining. While not a desperate measure, the mining represented a double-edged sword—with Halsey fully expecting to operate SOPAC forces here, minefields sown to catch the Japanese might very well cripple Allied vessels. Once the PT boat base in the Russells became active, and patrol craft were plying these waters regularly, the mines could become even more dangerous to Americans. The aspect of calculated risk was manifest.
Halsey also pursued the neutralization of Munda and Vila. By the time of Yamamoto’s I Operation, which obliged SOPAC to cancel a cruiser bombardment that Rear Admiral Ainsworth was to have carried out, the Japanese bases had been hit a good half dozen times. Beyond the cruiser forces, Admiral Halsey assigned destroyer units to these missions as well. Much like the Japanese at Guadalcanal, SOPAC commanders discovered that cruiser and destroyer bombardments appeared more effective than they actually were. Regardless of the weight of shells fired, the enemy air bases were typically in working order the next day. Naval bombardments supplemented constant air action. Three times Allied warships shelled Munda, the last on the night of May 12–13. The Vila base and nearby Stanmore Plantation were the targets on four occasions. Sometimes the bombardments were simultaneous, as on May 12–13, when Ainsworth’s cruisers hit Vila while Captain Colin Campbell’s destroyers shelled Munda. Since the JNAF had stopped actually basing aircraft, the number of planes vulnerable to these bombardments was small. Every cruise involved a danger of being caught by enemy warships or air strikes, so Halsey used the sorties to punctuate an aerial campaign.
