Members of the U.S. Marine Corps, Navy, and Coast Guard taking part in an amphibious assault during the “island hopping” campaign in the Pacific theater of World War II.

World War II has been called a “gross national product war,” meaning that its outcome turned on which coalition of combatants could outproduce the other. In retrospect, it appears inevitable that the entry of the United States, with its superior industrial might, would ensure the defeat of the Axis powers. But the first few months of American involvement witnessed an unbroken string of military disasters. Having earlier occupied substantial portions of French Indochina (now Vietnam, Laos, and Cambodia), Japan in early 1942 conquered Burma (Myanmar) and Siam (Thailand). Japan also took control of the Dutch East Indies (Indonesia), whose extensive oil fields could replace supplies from the United States. And it occupied Guam, the Philippines, and other Pacific islands. At Bataan, in the Philippines, the Japanese forced 78,000 American and Filipino troops to lay down their arms—the largest surrender in American military history. Thousands perished on the ensuing “death march” to a prisoner-of-war camp, and thousands more died of disease and starvation after they arrived. At the same time, German submarines sank hundreds of Allied merchant and naval vessels during the Battle of the Atlantic.

Although the Japanese navy never fully recovered from its defeats at the Coral Sea and Midway in 1942, it took three more pears for American forces to near the Japanese homeland.

Soon, however, the tide of battle began to turn. In May 1942, in the Battle of the Coral Sea, the American navy turned back a Japanese fleet intent on attacking Australia. The following month, it inflicted devastating losses on the Japanese navy in the Battle of Midway Island. These victories allowed American forces to launch the bloody campaigns that one by one drove the Japanese from fortified islands like Guadalcanal and the Solomons in the western Pacific and brought American troops ever closer to Japan.

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