Japanese Pre-WWII Navy Part I

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Japanese battleship Kirishima

In China and later in the Pacific, Japanese amphibious assaults were marked by surprise landings, often at night, at several spots simultaneously or in rapid sequence. Air and naval superiority were always present at the point of attack. Japan had no marine corps as such. The army was responsible for amphibious warfare and the navy for getting the troops to the invasion beaches and supporting the landings with gunfire and aviation. But Japan did possess an elite corps of “debarkation commandos,” special forces whose mission was loading the landing craft, moving them to the beaches, and returning the empty craft to the transports offshore. One keen student of Japanese warfare has observed that the nation’s warriors had a tendency to overplan, and “the more detailed the landing guidelines, the more difficult it became to hold to them.” This was the case when unexpected bad weather, high winds and surf, or unanticipated enemy resistance was encountered. As long as unforeseen difficulties did not occur, Japanese amphibious operations “ran like clockwork. But once a problem arose, confusion ensued,” and Japanese troops were likely to respond with foolish daring such as human-wave assaults in order to “win back full freedom to act.” Nonetheless, Japan conducted a series of major amphibious operations in China and the Pacific between 1937 and 1942 that rivaled in size and success those later undertaken by the Americans in North Africa, the Mediterranean, and the Gilbert, Marshall, and Mariana Islands between November 1942 and June 1944.

Japan’s preference for land-based naval aviation as an essential component of defensive warfare was given impetus by the war in China. Japanese forces followed up the Marco Polo Bridge Incident with a heavy air and land attack on the native sections of Shanghai. Within days, the army began a major thrust up the nearby Yangtze River valley toward Nanking and beyond, as Chiang Kaishek’s steadily retreating government lured the Japanese farther and farther from the coast.

Because of the vast distances involved, China inevitably became an air war— a strategic bombing campaign that in conception and scope if not scale prefigured those undertaken by the Allies over Europe after 1942. Such a campaign required the use of every plane and pilot in the Japanese arsenal. From the beginning, the navy consistently outperformed its army opposites in long-range bombing, often under terrible conditions of weather and terrain. Naval aircraft proved superb; the new Nell land-based bombers flew missions of up to 1,250 miles from Formosa and Kyūshū against targets in and around Shanghai, Nanking, Hankow (Hankou, now part of Wuhan), and other river cities. “The elation which swept the Japanese populace with the announcement of the bombing[ s] was understandable,” a Japanese historian recalled with chilling satisfaction. “We had a powerful, long-range, fair-and-foul-weather, day-and-night bombing force” with which to terrorize and kill thousands of civilians. Japanese casualties, however, were severe, especially during the first four months of the war, and until the end Japanese naval bomber aircraft, often unaccompanied by fighter escort until the advent of the Zero in 1939, were subjected to periodic savage maulings. Only in the crucible of battle did Japanese pilots learn the necessity of close-formation flying and at last master the art of dogfighting against skilled Chinese and Soviet pilots.

Carrier aircraft began making significant contributions to the Japanese offensive at Shanghai in August 1937 and continued to do so as the campaign moved up the Yangtze valley. The first generation of ship-based aircraft proved incapable of carrying out their missions, and the aircrews suffered terrible casualties. As late as the previous May, the fighter, dive-bomber, and attack aircraft aboard the Kaga were all biplanes. On August 17 the carrier launched its first strike against Chinese targets beyond Shanghai. A dozen Type 89 torpedo-bomber biplanes led by Lieutenant Commander Iwai roared down Kaga’s big flight deck and headed toward Hangchow (Hangzhou) to blast Chinese airfields. Only one plane returned. The bomber squadron failed to rendezvous with its fighter escort and had attacked alone.

The Japanese learned quickly from their mistakes. A year later Kaga had been joined by the smaller Hosho and the second-generation light carrier Ryujo, while Akagi completed a modernization program. From the beginning, the carrier air groups flying off Ryujo and Kaga were in the thick of the war. In late 1938 Akagi’s flyers joined the melee. The first carrier-based Type 89 attack bombers and then the Type 96 carrier-based fighters (Claudes) were badly mauled by the Chinese air force, increasingly manned with foreign volunteers and stocked with the best foreign aircraft. In response, Japan hurried new land- and carrier-based naval aircraft into production. “By importing many foreign aircraft and weapons,” two Japanese veterans of the campaign later wrote smugly, “we in Japan were able to gauge approximately what these weapons could and could not do. By keeping our planes and other armament within our borders and free from prying eyes, we led the world seriously to underestimate the combat strength of our naval aviation,” until the “China Incident” forced the Japanese to reveal how far their capabilities had advanced. In 1938–1939, Type 97 carrier attack bombers (Kates), Type 99 carrier dive-bombers (Vals), and the apex of Japanese aviation technology, the Zero fighter plane, all joined the fleet. As the Japanese army moved up the Yangtze beyond Nanking, chasing the always elusive Chiang and his forces, the carrier air wings moved ashore, following the army and bombing ahead of it in conjunction with the army air corps. By early 1940 land-based Nells, often escorted by Zeros or Claudes, were bombing Chungking, Chiang’s last haven of safety beyond the river gorges of the upper Yangtze more than a thousand miles west of Shanghai. Other bomber-fighter formations staging off carrier decks or, later, from advanced bases in Indochina ranged far and wide over southern China, ultimately closing down the vital Burma Road supply corridor.

The navy always boasted that its aviators were tougher and more adaptable than those in the army. Flyers and aircrew who trained ever more intensively for attacks against enemy surface fleets as the international situation shifted from Japan’s advantage in the late thirties nonetheless demonstrated from the earliest days of the China Incident an ability to strike land targets effectively. “Conversely, it was also determined that pilots trained specifically for maneuvers over land experienced great difficulty in over water operations, even in merely flying long distances over the ocean.”

In the mid-thirties as the carrier Ranger came into the U.S. fleet and Yorktown and Enterprise took shape in East Coast shipyards, the Imperial Navy bestirred itself to keep in step. Scarce funds were found to upgrade and modernize Kaga as well as Akagi. Training and war games had demonstrated that the best defense a carrier had was its own planes, and the unwieldy eight-inch batteries on both ships were removed. The crude three-deck hangar arrangement was abandoned, and the single flight decks were extended fore and aft to cover nearly the entire ship. As a result, Akagi’s and Kaga’s plane capacity increased from 60 to 90 (though both would normally carry about 72 planes in combat). At the same time, Japan pushed ahead with two ships roughly comparable to the American Yorktown class: the 34-knot Hiryu and Soryu, each 16,000–18,000 tons and capable of carrying at least 63 aircraft. A disastrous typhoon at sea in September 1935 damaged the fleet sufficiently to force designers to pay greater attention to strength and structural integrity. Both new Japanese carriers were built with higher hulls and forecastles. The carrier faction won an even greater victory in 1937 when it was able to place in the Fleet Replenishment Program orders for two superb 25,675-ton, 34-knot vessels to be named Shokaku and Zuikaku. Each ship embarked 72 aircraft, and each would be completed in 1941 in time to take part in the opening offensive of the Pacific conflict. On the eve of Pearl Harbor, Japan possessed six splendid frontline carriers—Akagi, Kaga, Hiryu, Soryu, Zuikaku, and Shokaku—that operating together as a fast mobile strike force, the Kido Butai, could deploy more than 350 aircraft. The Kido Butai displaced more than twice the tonnage allotted Japan by the Washington Conference.

Doctrinal and administrative progress kept pace with new construction. Experience in China had finally convinced Japanese carrier and fleet commanders that the attack aircraft at their disposal could best be employed—and protected— as a massed group. “Extending these realities to air war at sea slowly but inevitably led to the conclusion that carrier forces must be concentrated,” and by late 1940 the navy’s tacticians had hit upon the box formation as the best way to deploy carriers in a task-force configuration. Within months, Rear Admiral Jisaburo Ozawa had come up with another advance. Scattered as it was throughout the Pacific islands and on carriers, naval aviation in time of war would inevitably be employed incoherently and ineffectively. He convinced Yamamoto to create an air fleet within the Combined Fleet structure and to split it into land- and carrier-based components for maximum effect. At the end of 1941, the Eleventh Air Fleet, comprising eight land-based groups, was ready to lead the navy’s thrust southward toward the Philippines, Malaya, and the East Indies that would win Japan an empire within a few months. The First Air Fleet, encompassing all the aircraft deployed on the three carrier divisions, plus two seaplane divisions, composed “the single most powerful agglomeration of naval air power in the world,” including the U.S. Pacific Fleet. Just as each of Japan’s warships had to be qualitatively superior to fleet units in putative enemy navies, so Japanese naval aircraft had to possess greater speed, maneuverability, and, above all, range than comparable American—and British—planes. Japanese carrier aircraft were designed to deliver the critical first strike, to find and hit an enemy fleet before it could come in range to deliver aerial and surface blows of its own. Japanese carrier aircraft would have be lighter and more vulnerable than their U.S. opposites to achieve this objective, but as early as 1936 staff planners at Imperial Navy headquarters concluded that the key to success in any coming conflict “was to be mass attacks” by carrier aircraft “delivered preemptively because of the advantages of surprise and of ‘outranging’ the enemy.”