The Asia–Pacific War was caused by the expansionist ambitions of Imperial Japan, which by the 1920s had secured Taiwan, Korea and Manchuria. This strategy led to war with Nationalist China in 1937, and to provide fuel and supplies Japan seized the oil-rich Netherlands East Indies and Malaya. When the Japanese moved into southern Indo-China in 1941 the United States applied an oil embargo. Japan struck first at the US fleet at Pearl Harbor, hoping to form a defensive ring around its captured territories and reach an acceptable peace. But having been humiliated at Pearl Harbor, the United States would never have agreed to a negotiated peace.

The Allied strategy was largely reactive. To deter Japan, Britain applied the faulty Singapore Strategy. The US planned to advance gradually across the central Pacific, but were thwarted by Japan. Although the Allies’ overall strategy was to ‘beat Hitler first’, the United States continued to pursue and control the war in the Pacific. Given the industrial power of the United States, it was inevitable that it would prevail in the largely maritime war. By 1945 Japan was being strangled by the Allied blockade and conventional bombing. The atomic bombing of Hiroshima and Nagasaki in August 1945 forced Japan’s surrender.