WWII — The Pacific Theatre

From Pearl Harbor to Hiroshima: the war that made the United States a Pacific power.

Suggested next → Hiroshima & Nagasaki · HIST

The brief

Between December 1941 and August 1945, the United States and Japan fought a war across the largest battlefield in human history — the Pacific Ocean. Japan's surprise strike on Pearl Harbor on 7 December 1941 aimed to cripple the U.S. fleet and buy time to consolidate an empire; instead it united a divided America for total war. It was a war of naval aviation, amphibious assault, island-hopping campaigns, and — at the end — strategic bombing and atomic weapons. About three million Japanese died, perhaps twenty million Chinese died at Japanese hands over the longer war that began in 1937, and the conflict ended with the United States as the only great power whose homeland had not been physically devastated.

The Pacific War's strategic logic was logistic. Japan's initial conquests in the months after Pearl Harbor (the Philippines, Singapore, the Dutch East Indies, Burma) gave it an enormous defensive perimeter rich in oil and rubber — but the carrier battle at Midway in June 1942 cost Japan four fleet carriers and checked its offensive momentum barely six months in; the attrition around Guadalcanal then gutted the veteran naval air arm Japan could not replace. Japanese industry could never match American production once the U.S. economy was fully mobilized: by 1944 American shipyards were launching aircraft carriers faster than Japan could sink them. Above all Japan could not protect the shipping that connected its conquests to the resource-poor home islands; American submarine warfare strangled Japanese supply by 1944, sinking most of the merchant fleet and cutting the oil that had been the war's whole point. The island-hopping campaign (Tarawa, Saipan, Iwo Jima, Okinawa) bypassed Japanese strongpoints to seize airfields within bomber range of Japan itself, each at a savage cost that hardened American planning for the invasion to come. By summer 1945, American B-29s had firebombed scores of Japanese cities — the Tokyo raid of March 9–10 killed perhaps a hundred thousand people, more than either atomic bomb. The atomic bombs (Hiroshima August 6, Nagasaki August 9) and the Soviet declaration of war and invasion of Manchuria (August 8–9) destroyed both of Tokyo's remaining hopes: that the home islands could outlast American bombing, and that Moscow might broker a negotiated peace. Hirohito then intervened for surrender and broadcast it on August 15.

Why nowThe Pacific War's postwar settlement — American military bases in Japan, South Korea, the Philippines, Guam; the U.S.–Japan security treaty; the U.S. Seventh Fleet; a pacifist Japanese constitution written under occupation — is the infrastructure of the current Indo-Pacific. Contemporary U.S.–China rivalry plays out across the same geography, with the same chokepoints (Strait of Malacca, South China Sea, the Taiwan Strait), and most of the same alliance partners. Even Japan's decision, taken in 2022, to double defence spending by 2027 reopens a question this war was meant to close. The war did not so much end as shift opponents.