by John Prados
From them a smart analyst could derive the Japanese order of battle, its fleet organization, its leadership, even post office addresses. To have any chance at all of finding actionable intelligence, JICPOA had to deputize officers to scan for hot documents and embargo what they found. A forward translation team processed them immediately.
Similarly, until the Marianas, Japanese prisoners had been rare. The 1,780 prisoners captured on Saipan alone were more than those taken so far throughout the war. Coping with the bonanza of enemy soldiers required Admiral Spruance, plus the Army, the Navy, and the Marines, to pool intelligence resources. Prisoner interrogation, an art form Allied intelligence developed to a high level, began by asking each detainee a set of identical questions, designed to produce data that could be compared from one man to another, and elicit whether the prisoner possessed especially useful intelligence and should be questioned at greater length. The challenge seemed insurmountable. The JICPOA Interrogation Section expanded to twenty-four officers and twenty-seven enlisted, but even so most of the actual interviews took place elsewhere. Some 3,500 prisoners were interrogated at Camp Tracy in California (producing more than 1,700 data reports). The most sensitive questioning, usually of senior officers, took place at Fort Hunt, near Mount Vernon, Virginia.
Jasper Holmes and General Twitty kept in close touch with all the other Allied intelligence centers. Those in Washington, including the Office of Naval Intelligence (ONI) across the board, and OP-20-G for radio intelligence, were among their closest correspondents.
As Japanese officers promulgated orders to build strength for the big Sho battles, Commander Holmes wrote to ONI’s F-22 section, where Commander William J. Sebald, his counterpart, had charge of ONI’s estimates of Japanese strength. Sebald had proposed a new way to categorize aircraft. Holmes objected that available information would often be insufficient to make the choices. “Under present conditions,” Holmes wrote, “it is impossible for your people and mine to agree, [even] with ‘very wide limits,’ how many planes are in the Central Pacific, let alone attempt to classify them.”
On August 16, Holmes’s people issued a “special estimate” of Japanese fighter strength in the Inner Empire. Of a total of more than 2,200 aircraft projected, JICPOA saw 774 as belonging to combat units in training, with another 830 training pilots and aircrews. Just over 600 battle-ready fighter aircraft were in the assessment. Two-thirds of the fighters were in training!
Whatever else appeared, the intelligence revealed that Japan had begun frantic preparations.
CHAPTER 2
THE LOWDOWN
On July 25, the Japanese NGS operations chief sent out an all-hands warning: “KING HAS CONFERRED WITH NIMITZ IN HAWAII. THE NEXT ENEMY OFFENSIVE WILL BE DIRECTED TO THE PHILIPPINES AND WILL BE CARRIED OUT SHORTLY.” While Captain Yamamoto identified the American participants, he did not know that President Roosevelt stood on the verge of greeting his field commanders for the Pearl Harbor conference. He was also unaware that U.S. Navy chief King stood opposed to the Philippines option. It did not matter, though, because Japanese expectations were correct. The question that remained was what the Combined Fleet could do to defeat the offensive.
By this time most of Japan’s surface ships had arrived safely at Singapore or Lingga Roads, the southern bases, where they began strenuous combat exercises. Yamamoto’s dispatch heralded the fall of the last Marianas outposts. Vice Admiral Ugaki Matome, commanding Battleship Division 1, could imagine how bitterly this news was received at Combined Fleet headquarters. Ugaki had been the Combined Fleet chief of staff when the Allies captured Buna, in eastern New Guinea. His feelings of sorrow and regret had been nearly intolerable. Now, perfecting forces for the next battle became the best thing to do. Victory would not bring back the Marianas, but it might blunt the Allied advance.
There were immense immediate problems, however. Politics between NGS and the Combined Fleet command had often been touchy, and this battle threatened to bring them into play. An equally thorny problem existed between Navy and Army at Imperial Headquarters. The Navy Ministry meanwhile dealt with a host of difficulties ranging from rates of aircraft, engine, and warship production; to finding the metal for the manufacturing; to coping with the Allied technical superiority; to servicing and preparing the fleet for battle. And of course, all the Japanese efforts were under observation by an immensely capable Allied intelligence.
FORCE BUILDING
One reason the Japanese could not send a naval sortie to rescue beleaguered forces in the Marianas is that much of the fleet went through dry dock or construction yards as soon as the ships returned from their most recent battles. Even though the high command was anxious to return its forces to combat readiness as soon as possible, it would be no matter of scraping barnacles off ships’ bottoms, touching up their paint, or sticking on a few extra light antiaircraft guns. Rather, the summer and fall of 1944 witnessed the most concentrated burst of armament augmentation the Imperial Navy had ever seen.
Say what you like about the insanity of Japan’s war and the resource constraints that so often forced the Imperial Navy to make radical shifts in construction or deployment plans. Despite all of that, there is a certain logic that becomes apparent once the Japanese reached decisions. Even though their goals might be unobtainable, the Navy plotted reasonable directions toward them. After the Midway disaster, senior officers immediately convened to mull over shipbuilding changes and aircraft procurement. Now, two years later, conversions of battleships and seaplane tenders to hybrid or full aircraft carriers were available. New carriers were coming from the shipyards, and converted merchantmen—now escort carriers—were already on the high seas.
Japan had smart people wrestling with the production problems. At the top of the heap, Vice Admiral Hoshina Zenshiro headed the Military Preparations Bureau of the Navy Ministry. Hoshina had spent two years in the States, serving as an attaché in Washington and studying at Yale University, and thus he knew the Americans intimately. Once the captain of the battleship Mutsu, which had sunk due to an accidental explosion in September 1943, Hoshina now felt a special sense of duty to protect sailors. His department supervised production of ammunition, along with the radars and new technical equipment that officers hoped would transform the Imperial Navy.
Hoshina’s combat preparations specialist was Captain Oishi Tamotsu, chief of the 1st Section. Oishi had previously served as a senior staff officer to Nagumo Chuichi, the swashbuckling carrier boss at Midway so recently lost in the battle for the Marianas, and had also been navigator for one of Japan’s most renowned surface commanders, Kondo Nobutake. Though not a pilot, Oishi had a reputation as a close observer, and he listened to reason.
In addition, Admiral Hoshina had close ties with Vice Admiral Oka Takazumi, chief of the ministry’s Military Affairs Bureau. Together, Military Preparations and Military Affairs took the lead in shaping the Imperial Navy’s doctrine and equipment. Oka’s bureau also set the Navy response to general political developments. And in conjunction with the Naval Technical Bureau, the Military Affairs Bureau matched available budgets with the shipbuilding and modification program.
Admiral Oka, a submariner, had gained renown as an oil expert. Well aware that Allied subs were slaughtering Japan’s tankers, he faced daily complaints of the difficulties of obtaining fuel in the Home Islands. Basing the surface fleet in the southern area eased the headaches of obtaining fleet oilers for a naval sortie.
The other side of that coin, however, was the hostile aerial environment. In this operation the fleet would need to make a lengthy approach across waters dominated by Allied aircraft. If the Sho contingency materialized in the Philippines, that meant steaming more than 1,300 nautical miles into the Allies’ clutches. The other Sho theaters were even more distant. Fleet antiaircraft defense could not be solved by means of fighter interceptors, land or carrier based.
The Japanese were aware of their shortcomings in fleet
antiaircraft defense and were already taking measures to close the gap. Captain Oishi understood from the Marianas battle that the Navy would face a hostile air environment regardless of its own aerial strength. Tokyo’s system made the Naval Technical Department the center of warship design and construction. Oishi and Hoshina cooperated with Vice Admiral Sugiyama Rokuzo, who headed this ministry unit. Much of Sugiyama’s experience had come in the China Incident, where at various times he had been both chief of staff and fleet commander, as well as a leader of operating units. But the admiral had been a battleship skipper too. He knew the problems of surface ships in an air age and was an Etajima classmate of such officers as Kusaka Ryunosuke, now Combined Fleet chief of staff; and Mikawa Gunichi, the Navy’s top leader in the Philippines.
The Naval Technical Bureau moved affirmatively to strengthen flak defenses. Akitsuki-class destroyers, designed as antiaircraft ships, were modified in midprogram to become even stronger, with a complement of eight 3.9-inch dual-purpose guns and forty 25mm automatic cannon. The lead redesigned destroyer, Fuyutsuki, joined the fleet in May 1944, right before the Philippine Sea debacle. Similarly the light cruiser Isuzu, already in the yard, would emerge in mid-September as an antiaircraft cruiser armed with a half dozen 5-inch antiaircraft guns but no fewer than fifty 25mm weapons. But it would be months until more Akitsukis joined the fleet, and the Japanese had no cruisers to spare for conversion like the Isuzu.
The Imperial Navy did something more ambitious. Admirals Sugiyama and Hoshina, in conjunction with Combined Fleet commanders, determined to up-gun pretty much the entire fleet. Fleet boss Toyoda, who had headed the Naval Technical Bureau before the war, gave his complete support. Every aircraft carrier, every battleship, nine of eleven light cruisers, and all but four of the roughly fifty destroyers were given strengthened antiaircraft armament. Of the thirteen Imperial Navy heavy cruisers, all but two had construction workers swarming over them immediately after the Philippine Sea battle. The Kure and Yokosuka Naval Districts did most of the work. The yards installed more than 300 additional 25mm flak pieces in the heavy cruisers alone. And the Navy deployed a new weapon, the 5-inch antiaircraft rocket, placed on carriers and battleships. Every major vessel without a radar now received one. Many got additional, more sophisticated sets, including models that could control the fire of heavy guns.
All of this amounted to a huge increase in defensive firepower. The post–Philippine Sea battle fleet upgrade included the installation of more than 1,650 5-inch rocket launchers, 20 dual-purpose 5-inch powered gun mounts, nearly 2,000 of the 25mm antiaircraft guns, and more than 200 13mm flak pieces. Plus there were the antiaircraft ships starting to join the fleet. In terms of air defense, the Combined Fleet rose from the ashes of the Marianas as a more powerful force.
THE AIR ARMADA
The headaches of fitting out the fleet, however, paled next to the dilemmas of refashioning its air arm. The First Air Fleet had effectively been destroyed over the Marianas and had to be completely rebuilt. There was little alternative except to press ahead. Land-based aircraft provided the Japanese Naval Air Force (JNAF) with its heft. The carrier air groups that had been its elite were now so debilitated there was no alternative to emphasizing air fleets over carrier groups.
Vice Admiral Teraoka Kimpei took over a re-created First Air Fleet. Under the Sho plan, which provided roles for multiple air fleets reinforced with Army air divisions, on July 10, Admiral Toyoda reorganized the JNAF and created the Second Air Fleet. This was a major formation that Toyoda hoped would swing the odds in battle. On July 11, the Third Air Fleet, led by Vice Admiral Shunichi Kira, with Rear Admiral Miura Kanzo serving as chief of staff, formed as the JNAF’s central training outfit. The reorganization consolidated or eliminated a host of battered fighter or bomber groups. The Third Air Fleet was a key to their future plans. Based in the Home Islands, it would be both the air force reserve and the key organization preparing crews for battle. Admiral Shunichi’s mission was simple—to jump-start flight training for the JNAF so that as the Allies began to bomb Japan, his air fleet would become the Empire’s sky defense as well.
Despite the reorganization, aerial preparations faced enormous obstacles. In September, Shunichi’s headquarters released a study that revealed how deep the problem had become. The paper surveyed aircraft readiness and crew skills in several air groups across the force over the fleet’s early months. Of nearly 500 pilots and crews, Third Air Fleet staff evaluated just 77 as fully capable, with 58 others reliable for daytime missions only. All the rest it judged insufficiently trained. In a fighter group with 232 pilots, there were 17 able men and 9 more pilots ready for daytime flying.
The pilot and crew situation may have been a mess, but the aircraft situation looked abysmal. For instance, Captain Fujimatsu Masahisa’s 252nd Naval Air Group, a fighter unit bloodied in the Solomons, particularly at the Battle of the Bismarck Sea, had fewer than forty planes—aircraft whose average flight availability hovered around 40 percent. On July 10, the group added several flying units. Some pilots went to another veteran unit, the 201st Air Group. Admiral Shunichi assigned the 252nd to his old northern Pacific command, the 51st Air Flotilla.
The 752nd Naval Air Group, renowned in the JNAF for its actions in the northern theater, at Rabaul and in the Central Pacific from November 1943, had been re-formed in Japan earlier in the year, in February. As a result, the 752nd was a little better off than most, with twice as many planes as the fighter group, and within its twin-engine bomber unit, it accounted for two-thirds of the air fleet’s qualified crews. However, the average flight ability remained about the same as that of the 252nd.
There were exceptions, of course—the most prominent of which would be the T Air Attack Force. As the war progressed, the JNing Allied superiority and adopted new tactics in an attempt to equalize the odds. One of these measures had been training units to specialize in night attacks, and the T Air Attack Force represented an evolution of that idea.
The unit was activated in March 1944, under the direct command of the Combined Fleet, and Fukudome Shigeru took credit for the development. As a midlevel officer in the 1930s and the top operations planner for the Combined Fleet at the time, Fukudome had championed an idea known as “foul weather training.” The Imperial Navy had had to give up the practice after a storm capsized one of its warships with massive loss of life, and Fukudome had been forced to resign his post. But the T Air Attack Force brought back that idea—the T stands for “typhoon”—and the unit came under the Second Air Fleet in mid-June. Led by Captain Kuno Shuzo, one of the Navy’s most experienced pilots, who had fought in the Solomons and gained fame at Rabaul, this would be an expert bombing unit. The T Air Attack Force was exceptional for another reason too—for the first time Japanese Army Air Force regiments were assigned to a Navy unit.
Preparing the T Air Attack Force became a race against time. Captain Fuchida Mitsuo, the Pearl Harbor attacker, helped train the Army airmen, but unfortunately, he was called away to join the Combined Fleet staff before he could complete the program. Though the force was not ready in time for the Marianas battles, Captain Kuno continued to drill his crews in bad weather and at night.
For the Army, which usually avoided flying its planes over the ocean, the duty could be terrifying. Admiral Fukudome argued that several years of training were necessary for a special unit like this. By that standard none of Kuno’s crews were proficient. The first of the Army’s air regiments, the 98th, joined the T Force in April 1944, when there were enough of the new Ki-67 “Peggy” twin-engine bombers to equip it. The 7th Air Regiment received its bombers only after the Sho operation had been devised. Fukudome honestly believed that in a night battle—under conditions intended for the T Air Attack Force—the Army crews would have no idea whom they were attacking. Nevertheless, the admiral records of the T Force, “I placed my greatest reliance for victory upon this unit.”
The 343rd Naval Air Group at Tateyama were
also an exceptional unit. Its pilots flew Japan’s new Shiden fighters. The JNAF created the group at Kagoshima at the beginning of 1944, under Commander Takenaka Masao, a former flying boat driver. The 343rd started with Zeros—since new planes were not ready yet—and only half a dozen of its pilots, just one-tenth of the initial complement, were experienced. But by the time of the Marianas sea battle, Takenaka, who had a reputation as a fine trainer, had whipped them into some kind of shape. But for every unit like the 343rd, there were many JNAF groups challenged just to put a formation in the air.
• • •
KISARAZU BASE, WHERE much of the 752nd Group roosted, held an important role for the Navy, in addition to being the air fleet’s headquarters: It housed the No. 2 Naval Air Depot, a place where the fleet took possession of aircraft production. Warplane quality figured in flight readiness, in-flight performance, fuel consumption, and combat survivability.
As the war progressed and Allied forces, especially submarines, destroyed more of Japan’s resources every day, the Navy had to cut back the amount of steel and aluminum it devoted to aircraft fabrication. Until 1942, the Imperial Navy had not made any effort to calculate the raw material required for programmed aircraft production. That had been a mistake. The first new assessment allotted 4.5 tons of aluminum per plane—which was much too little. In 1943, planners revised the allotment to 5.5 metric tons.
Actual consumption in aircraft built after the Marianas battle reverted to 4.7 tons, near the former figure. But this proved extravagant compared to the end of 1944, when Japan could spare only 2.4 tons of aluminum per aircraft. A Zero fighter toward the end of the war weighed about 6,000 pounds. An American medium bomber like the B-26 clocked in at ten times that weight. Allied aircraft had weight to spare for armor and survivability features.