JAPAN ADOPTS “ABSOLUTE DEFENSE PERIMETER” STRATEGY

Tokyo, Japan September 30, 1943

On this date in 1943, at the fourth Imperial Con­fer­ence held since the start of the Pacific War, senior Japanese mili­tary and civil­ian leaders adopted the “abso­lute defense peri­meter” stra­tegy after securing the requi­site impri­ma­tur of Shōwa Emperor Hiro­hito. The stra­tegy reflected a shift in the expec­ta­tions of both the emperor and Japan’s mili­tary leader­ship in light of the accel­erating reverses suffered by Japa­nese armed forces since the naval dis­aster at Mid­way (June 3–7, 1942). That was when Japa­nese hopes were dashed for a second demor­alizing Ameri­can defeat (the first had occurred on Decem­ber 7, 1941), a defeat intended to force the United States to capitu­late in the Pacific War and thus ensure Japan’s domi­nance of the Western Pacific ocean. In a meeting at Imperial Head­quarters on Decem­ber 31, 1942, staff was advised that the emperor now feared that Japan might lose the war.

In the spring of 1943, Hirohito shared his thoughts with a few imperial court inti­mates about con­tinuing the war and about pushing for an early con­clu­sion of hosti­lities. The late May loss by sui­cidal attacks of the entire Japa­nese garri­son at Attu in the North Ameri­can Aleu­tian Islands was a hinge moment in Hiro­hito’s thinking: from June 8, 1943, the emperor began insisting that his army and navy coor­di­nate joint opera­tions in a single deci­sive frontal attack in the Pacific so that Japan could claim a victory over the U.S. before negotiating favorable peace terms with the Allies.

The “absolute zone of national defense” agree­ment of Septem­ber 30, 1943, turned its back on Japa­nese expan­sion in the Pacific to one of holding the line. The stra­tegy called for Japan’s armed forces to main­tain the 1943 front lines until they could rebuild their strength for a final deci­sive battle in mid-1944. The stra­tegic southern peri­meter, to be strongly manned and forti­fied, ran from Western New Guinea to the Mari­ana Islands via the Caro­lines (see map). Defense prepa­ra­tions behind the line were to be completed by the spring of 1944.

Unfortunately for the Japanese, the national defense zone was over­run before it was ever com­pleted. By Novem­ber 1943 U.S. Adm. William Halsey’s forces, oper­ating from Guadal­canal (evac­u­ated by the Japa­nese the pre­vious Febru­ary), had advanced up the Solo­mon chain as far as Bougain­ville (right bottom corner of map). Two months later Allied forces had reached Cape Glou­cester on the western end of New Britain Island, virtually com­pleting the out­flanking of the Japa­nese strong­hold of Rabaul at the eastern end (identi­fied by the long blue arrow out­side the defense zone). U.S. and Austra­lian forces raced to the western end of New Guinea by mid-1944, forcing the Japa­nese to retreat west­ward to the Dutch East Indies. In Octo­ber, with the southern peri­phery of Japan’s National Defense Zone in tatters, Gen. Douglas MacArthur invaded the Japanese-held Philip­pines. That move pro­vided Halsey’s fleet with the oppor­tunity to sink most of the remaining major Japa­nese sur­face ships at the Battle of Leyte Gulf (Octo­ber 23–26, 1944), for­ever depriving Hiro­hito and his armed forces of a favorable site for any decisive showdown with the United States.





Whittling Away at Japan’s National Defense Zone

Japan’s National Defense Zone, September 1943

Above: The southern periphery of Japan’s outer ring of defense in the Pacific, Septem­ber 1943. The south­east sector was deemed of vital impor­tance to the stra­tegic national defense of the Japanese home­land, its southern bound­ary to be fixed, behind which air, naval, and ground strength could be replen­ished and marshaled for a deci­sive victory over the Americans and their allies. Victory eluded the Japa­nese in a series of mili­tary defeats and retreats in the Pacific and South­east Asia due partly to the inten­sifying rivalry between the Japanese Army and Navy and partly to the application of superior Allied resources.

Japanese transports beached and burning, Guadalcanal, November 1942 Marines wade ashore at Cape Gloucester, New Britain, December 26, 1943

Left: Japanese transports Hirokawa Maru and Kinugawa Maru beached and burning after a failed resupply run to Guadal­canal on Novem­ber 15, 1942. The Battle of Guadal­canal (August 7, 1942, to Febru­ary 9, 1943) was the first major ground offen­sive by Allied forces against Japan. Japa­nese loses numbered over 19,000 dead, 38 ships, and between 680 and 800 aircraft.

Right: Marines hit three feet of rough water as they leave their landing craft to take the beach at Cape Glou­cester, New Britain, Terri­tory of New Guinea, Decem­ber 26, 1943. The Battle of Cape Glou­cester took place between late December 1943 and April 1944 and cost the lives of 310 Amer­i­cans and 1,000 Japanese. The battle was one of ten sub­ordin­ate opera­tions in Opera­tion Cart­wheel, the chief Allied strategy in the South­west Pacific Area and Pacific Ocean Areas during 1943–1944.

U.S. landing at Cape Sansapor, New Guinea, July 30 or 31, 1944 Gen. Douglas MacArthur landing on Leyte, October 20, 1944

Left: The deck of this landing craft is closely packed with motorized fighting equip­ment en route for the inva­sion of Cape Sansa­por, Western (Dutch) New Guinea. The Battle of Sansa­por (July 30 to August 31, 1944) was an amphib­ious landing and subse­quent opera­tions around Sansa­por. The battle, costing 14 U.S. killed versus 385 Japanese killed and 215 captured, was one in a series of actions during the Western New Guinea Campaign (April 22, 1944, to August 15, 1945). Gen. MacArthur’s last point of landing en route to retaking the Philippines was at Sansapor.

Right: Making a dramatic entrance, Gen. Douglas MacArthur and staff, accom­panied by Philip­pine presi­dent Sergio Osmeña (left in pith hel­met), wade through surf onto Red Beach (Palo Beach just south of Taclo­ban), Leyte, on Octo­ber 20, 1944, shortly after the start of the Battle of Leyte (Octo­ber 17 to Decem­ber 26, 1944). Once on shore MacArthur spoke into a micro­phone, reading his prepared text with great emo­tion: “People of the Philip­pines, I have returned! By the grace of Almighty God, our forces stand again on Philip­pine soil—soil conse­crated in the blood of our two peoples. . . The hour of your redemp­tion is here.” The battle for Leyte, one of the larger islands of the Philip­pines, cost the U.S. just over 3,500 killed and 12,000 wounded. Japanese dead were roughly 49,000.

War in the Pacific: U.S. Army’s “Big Picture,” a Two-Part Documentary (May want to skip the first minute and last 20)


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