World War II Day by Day

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 in the Pacific

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.

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: Heavily laden advance guards of the U.S. 1st Marine Divi­sion hit 3 feet/­0.9 m of rough water as they leave their landing craft to take the beach at Borgen Bay north­east of 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 1 of 10 sub­ordin­ate opera­tions in Oper­a­tion Cart­wheel, the chief Allied stra­tegy in the South­west Pacific Area and Pacific Ocean Areas during 1943–1944.

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 2 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,” Part Two, June 1944–1945