Islands of Destiny: The Solomons Campaign and the Eclipse of the Rising Sun (45 page)

The next day in Rabaul passed with reviews of New Guinea events. The responsible Army general, plus Navy staff officer Ohmae, had both done surveys. The military situation appeared better than in the Solomons. On the other hand, the need to cross high mountains complicated air attacks. Bad weather crossed the Bismarcks toward Papua. At the final briefing on April 9, with admirals Kusaka and Ozawa both pleading for more preparation time and the weather still uncertain, Yamamoto approved a delay. As the planes were prepped, staff chief Ugaki visited the command posts of the 21st and 26th air flotillas. Plans were altered again to protect the vulnerable Betty bombers, postponing their participation so as to arrange stronger fighter escorts. The initial New Guinea strike took place on April 11 against Oro Bay.

It was a Sunday, like Pearl Harbor. Oro Bay, a dozen miles south of Buna, was one of MacArthur’s supply centers for the area. Milne Bay, the other, not far away, was stuffed with shipping. Kusaka’s Eleventh Air Fleet had been flying against Oro Bay for a month, and the raid of April 11 had been preceded by a half dozen others. This strike would be carried out by carrier aircraft alone, with
Zuiho
fighters in an initial sweep, a
Zuikaku
formation following, and Kakuta’s warplanes bringing up the rear. Without Guadalcanal’s extensive warning net, the defenders got just a few minutes’ notice. Fighter interceptors scrambled from nearby Dobodura, but many engagements occurred only as the enemy retired. Ozawa’s
Kido Butai
air groups contributed a swarm of seventy-two Zeroes and twenty-two Vals. The “sea eagles” sank a 2,000-ton freighter and damaged another merchantman plus an Australian minesweeper. They lost four dive-bombers and two fighters, though Allied claims amounted to seventeen JNAF aircraft. General Kenney could not understand why the enemy had not hit Milne Bay, and ordered most of his interceptors, more than a hundred fighters, to Dobodura, north of the Owen Stanleys, where they would be in ideal position.

Admiral Yamamoto rose early the next morning, at Lakunai by 4:30 a.m.
to send off the medium bombers for their ambitious Port Moresby strike. Next to Guadalcanal, Moresby, having endured more than a hundred air raids since the war started, was undoubtedly the favorite Japanese target. It was also the most heavily defended, with many airfields and many Fifth Air Force warplanes. Forty-three Betty bombers, directly escorted by seventy-six Zeroes of the land-based air groups and the carriers, made the hit. They were in two assault formations led by Commander Nakamura Tomo of the 705th Air Group and Lieutenant Commander Suzuki Masaichi of the 751st. Some fifty-five Zeroes of the
Zuikaku
,
Hiyo
, and
Junyo
conducted a roving fighter sweep. Warrant Officer Morinio Hideo claimed three planes flamed, a substantial contribution to the nineteen planes believed destroyed with six probables that day.

This time the Allies had warning. The CINCPAC intelligence summary predicted an air attack. Radar picked up the attackers northeast of New Guinea. General Kenney scrambled his Dobodura fighters to defend Milne Bay, the supposed target. But radar lost the Japanese, only to reacquire them near Port Moresby. There the Fifth Air Force had just eight P-38s and twelve P-39s. Allied airmen could not stop the bombers, which attacked from 18,000 feet, but they inflicted losses. Despite direct escort by thirty-two Zeroes from the
Zuiho
and the 253rd Air Group, Commander Nakamura’s unit lost half a dozen Betty bombers. Suzuki’s second wave, covered by forty-four Zeroes of the 204th and 582nd air groups, had several Bettys damaged. Kenney, meanwhile, ordered the mass of his fighters toward Lae, where he assumed the JNAF would land. When the strikers headed for Rabaul instead, fewer than two dozen interceptors had the fuel to catch them and flame a few more enemies. The Japanese believed they had damaged eleven airfields. While that was exaggerated, as usual, even American accounts concede injury to four, with nineteen aircraft hurt or wrecked on the ground and two shot down, against the loss of six Bettys and two Zeroes (Fifth Air Force claimed fifteen bombers and nine to ten fighters downed). This success did not prevent American B-17s from harassing Rabaul with a bombing of their own.

Then came the Milne Bay attack, on April 14 shortly after noon. The CINCPAC intelligence summary, partly right, partly off, tentatively predicted a strike, but not on the scale of Guadalcanal or Moresby. Dobodura was fog-bound at the critical moment, and most of Kenney’s fighters were
unable to launch. Out of more than a hundred planes, eight P-38s and thirty-six P-40s engaged. Not enough, though only a couple were lost. Two of the P-38s that fought were those of the 9th Fighter Squadron’s Lieutenant Richard Bong and his wingman. Befogged early on, Bong managed to catch the later wave and thought he bagged at least one before a Zero damaged his plane and sent him home. Analyzing historical data, aviation historian Henry Sakaida concluded that Bong had actually destroyed
three
JNAF bombers. Lieutenant Bong soon ranked among the top American aces of the Pacific war.

In waves totaling 187 aircraft, a third of them bombers, the Japanese attacked. The lead strike unit comprised Bettys accompanied by fifty-six land-based fighters. The follow-on force consisted of Ozawa’s carrier planes, Vals, plus no less than seventy-five Zeroes. The raiders claimed to have sunk six transports, damaging nine; and to have set afire land targets, destroying forty-four aircraft. A gasoline dump was indeed blown up, and a ship sunk. Two merchantmen suffered damage. These results were paltry. Under the circumstances, the statement that day from Emperor Hirohito, which lauded the I Operation, seemed overdone. Ten JNAF aircraft never came back. SOWESPAC informed Washington it had downed ten bombers and five fighters, with eight more bombers and a fighter as probables, plus four bombers and two fighters damaged, a total of thirty planes.

At this juncture, mindful of the need to preserve the air units, Admiral Yamamoto curtailed his offensive. Possibly the main impact was on morale. Petty Officer Igarashi Hisashi of the 705th Air Group told his diary that the carrier pilots had been “a good stimulus to our land-based attack units as they tend to be in low spirits.” Yamamoto ordered Ozawa’s carrier planes back to their ships on April 16. Chief of staff Ugaki, ill with dengue, recovered enough to preside over an operational review at Eighth Base Force headquarters. The Japanese believed they had destroyed ninety-five aircraft (plus thirty-nine probables), sinking a cruiser, two destroyers, and twenty-five transports. The true results were a tiny fraction of that. Ugaki praised the “sea eagles” but observed that airpower remained the key long-term problem. He exhorted everyone to greater effort. In the audience Commander Okumiya listened as officers fussed that just four missions had cost fifty planes. In particular the bomber losses could not be sustained. The aircraft needed more protection. Allied air was better—and stronger. Japanese
striking power was waning. “The meeting concluded in a pessimistic air,” Okumiya recalled.

Before returning to Truk, Yamamoto Isoroku wished to visit Bougainville. The C-in-C knew that Army troops from his hometown had been evacuated there after Guadalcanal. A trip to the bases could also buck up the airmen. Yamamoto broached the idea on his second day at Rabaul and later reaffirmed his intention. Admiral Ugaki desired to inspect outposts as far afield as Munda and Vila. That was simply not practical. He put Commander Watanabe Yasuji to work on the arrangements. Ugaki concerned himself with the public relations aspect—he wanted pictures of Yamamoto in the Imperial Navy’s combat utility uniform—all existing photos of the fleet commander had him in service blues or whites, more formal garb. The afternoon of April 17, Ugaki also fretted over whether the travel party should go in neckties or with open-necked shirts (not regulation uniform). He decided the former.

That evening Yamamoto dined at the officers’ club with Kusaka and Ozawa along with several other classmates of Etajima 1909. Yamamoto was not of that class, but he had been on their training cruise. Yamamoto brought a bottle of Johnnie Walker Black Label Scotch, his favorite drink since living in America. Perhaps it was fitting that the admiral should enjoy some before meeting his destiny. Ozawa begged Yamamoto not to fly, or at least to take along a cloud of his carrier fighters. The C-in-C brooked no change. Not just Yamamoto and Ozawa had an inkling of disaster—two more men warned the C-in-C that very day. General Imamura went to Yamamoto and recounted how, several months earlier, his plane had been accosted by a pack of American fighters and had escaped only by hiding in a cloud bank. Imamura intended this as a warning, and encouraged Yamamoto to go by boat. Rear Admiral Joshima Takatsugu of the R Area Force had also warned Yamamoto not to fly. Joshima had seen the cable traffic on the Bougainville visit. Disturbed at the large number of addressees, plus the detailed schedule and itinerary, Joshima became apprehensive when he learned that two bases had exchanged the identical trip information in a less secure aviation code (it remains unclear whether this was the one the Americans possessed). Admiral Joshima hopped a seaplane to Rabaul and laid his fears before Yamamoto. The C-in-C shrugged it off. Yamamoto invited
Joshima to breakfast together upon his return. Yamamoto’s bravura gesture proved empty.

“WE’VE HIT THE JACKPOT!”

Commander Watanabe took a little more than a week to complete Yamamoto Isoroku’s itinerary. The admiral would fly from Lakunai, first stop Ballale in the Buin complex. Five days in advance, on April 13, Watanabe put details into a dispatch he sent to all concerned commands. The message included a schedule, specified what transportation Yamamoto would use at each stage, and noted the admiral’s intention to inspect facilities and see the sick and wounded. Helpfully, Watanabe noted that if the weather was bad the trip would be postponed a day. Watanabe took such care that he calculated the extra time required to boat back from one location due to running against the tide. Watanabe specified that the travel party would be escorted by six fighters. Almost the only detail he left out was to note the fleet staff’s practice of putting C-in-C and chief of staff in different aircraft so the top leadership could not be wiped out by a single plane crash. As far as radio intelligence was concerned, Commander Watanabe had some doubts about the security of Army codes, so he ordered that the message be sent only in the D Code—that is, JN-25. The dispatch went out from Southeast Area Fleet late that afternoon.

The Yamamoto trip notice promptly found its way to Allied codebreakers. FRUPAC and Negat picked it up immediately, and FRUMEL obtained a later retransmission as well as the text recirculated by U.S. intelligence on the Copek circuit. Both Pearl Harbor and Washington immediately plunged into recovering this message. Though the Imperial Navy had changed its additive table on April 1, complicating work with JN-25, many values had already been recovered, especially oft-repeated terms like names of commands and places.

Lieutenant Roger Pineau at FRUPAC later recorded that the large number of addressees for Watanabe’s dispatch had instantly drawn attention. The cryptanalysts—at FRUPAC the aces were Tommy Dyer and Ham Wright—worked to strip the additives off the code groups. Traffic analysts—here the experts included Tom Huckins and Jack Williams—established the address
information and geographic locator designations, assisted by Jasper Holmes. Then the code groups of the underlying message were revealed. By now the codebreakers were using new technology, the IBM mechanical card-sorting machines, to help break messages. Each code group in a message would be punched onto a card, and the sorter would run the cards against another set containing known JN-25 meanings. Experts penetrated the unknowns by considering their position in sentences, and comparing the appearance to their usage in other messages. Once a basic version of the original—or “plaintext”—had been recovered it was ready for the language experts, in this case Marine Major Alva B. “Red” Lasswell and Lieutenant Commander John G. Roenigk. The Navy officer saw the Marine leap to his feet.

“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.”