of Sakhalin. Japan's population grew from 35 million in 1873 to 70 million in 1935.
The early 20th century saw a brief period of "Taishō democracy" overshadowed by increasing expansionism and militarization. World War I enabled Japan, on the side of the victorious Allies, to widen its influence and territorial holdings. It continued its expansionist policy by occupying Manchuria in 1931; as a result of international condemnation of this occupation, Japan resigned from the League of Nations two years later. In 1936, Japan signed the Anti-Comintern Pact with Nazi Germany, and the 1940 Tripartite Pact made it one of the Axis Powers. In 1941, Japan negotiated the Soviet–Japanese Neutrality Pact.
The Empire of Japan invaded other parts of China in 1937, precipitating the Second Sino-Japanese War (1937–1945). In 1940, the Empire then invaded French Indochina, after which the United States placed an oil embargo on Japan. On 7 December 1941, Japan attacked the US naval base at Pearl Harbor and declared war, bringing the US into World War II. After the Soviet invasion of Manchuria and the atomic bombings of Hiroshima and Nagasaki in 1945, Japan agreed to an unconditional surrender on 15 August. The war cost Japan and the rest of the Greater East Asia Co-Prosperity Sphere millions of lives and left much of the nation's industry and infrastructure destroyed. The Allies (led by the US) repatriated millions of ethnic Japanese from colonies and military camps throughout Asia, largely eliminating the Japanese empire and restoring the independence of its conquered territories. The Allies also convened the International Military Tribunal for the Far East on 3 May 1946 to prosecute some Japanese leaders for war crimes. However, the bacteriological research units and members of the imperial family involved in the war were exonerated from criminal prosecutions by the Supreme Allied Commander despite calls for trials for both groups.
In 1947, Japan adopted a