For China the war began not in 1939 but in July 1937, when a clash at the Marco Polo Bridge near Beijing grew into full-scale war with Japan. Japan's leaders had come to believe that their country, short of raw materials and shut out by Western tariffs and racial barriers, needed an empire on the Asian mainland. Japanese forces took Shanghai and then the Nationalist capital, Nanjing, where in December 1937 and the weeks that followed soldiers murdered prisoners and civilians and raped tens of thousands of women. Estimates of the dead vary widely: the postwar Tokyo tribunal accepted a figure over 200,000, the Chinese government gives 300,000, and some Japanese scholars give much lower numbers. Denial of the massacre by some Japanese nationalists remains a painful issue in East Asia.
China did not collapse. The Nationalists under Chiang Kai-shek retreated inland to Chongqing, the Communists under Mao Zedong fought a guerrilla war in the north, and these uneasy partners tied down much of Japan's army for eight years. China's losses were immense, with common estimates of 15 to 20 million dead.
The road to Pearl Harbor
Japan presented its expansion as liberation. Its leaders spoke of a Greater East Asia Co-Prosperity Sphere, promising to free Asia from Western colonial rule under Japanese leadership. After France fell, Japan moved into northern French Indochina. When Japanese troops occupied the south of Indochina in July 1941, the United States froze Japanese assets and cut off oil, and Britain and the Dutch followed. Japan imported most of its oil from the United States, so its leaders faced a choice: pull back from China and Indochina, or seize the oil fields of the Dutch East Indies and risk war with America. They chose war.
On 7 December 1941 Japanese carrier aircraft struck the US Pacific Fleet at Pearl Harbor in Hawaii, while other forces attacked Malaya, Hong Kong, the Philippines and Guam within hours. The raid killed about 2,400 Americans and sank or damaged eight battleships, but the American carriers were at sea, and the base's fuel tanks and repair yards were left largely intact. Four days later Hitler declared war on the United States, joining the European and Asian wars into one global conflict. For six months Japan swept all before it. In February 1942 Singapore, Britain's great base in Asia, surrendered to Japan, and some 80,000 British, Indian and Australian troops went into captivity in one of the worst defeats in British history. In the Philippines, American and Filipino troops who surrendered on Bataan in April 1942 were force-marched to prison camps, and thousands died on the way.
The turn of the tide
In June 1942 the US Navy, warned by codebreakers who could partly read Japanese naval signals, ambushed the Japanese fleet near Midway Island. At Midway Japan lost four aircraft carriers and many experienced pilots, losses it could not make good. From August 1942 to February 1943 Americans and Japanese fought a grinding campaign for Guadalcanal in the Solomon Islands. The Allies then adopted island hopping, bypassing strongly held islands to seize others that could serve as air bases closer to Japan, leaving bypassed garrisons cut off. Australian and American troops fought through New Guinea, and British and Indian forces turned back a Japanese invasion of India at Imphal and Kohima in 1944.
Life in Japan's empire
For the people of occupied Asia the promise of liberation proved hollow. Some nationalists cooperated with Japan, hoping to end European rule, but occupation brought requisitions, forced labor and brutality. About 60,000 Allied prisoners and more than 200,000 Asian laborers were forced to build the Burma-Thailand railway, where forced laborers died in huge numbers: over 12,000 prisoners and tens of thousands of Asian workers. The Japanese military set up a system of so-called comfort stations in which tens of thousands of women, many of them Korean, were held in sexual slavery. Unit 731 in Manchuria carried out lethal experiments on prisoners. Rice requisitions and disrupted trade helped cause famines, including one in northern Vietnam in 1944 and 1945 that killed hundreds of thousands, perhaps far more.
Worked example: liberation or empire?
Suppose a Burmese nationalist in 1942 must decide whether to welcome the Japanese. Britain has ruled Burma for generations and refused full self-government. Japan promises independence, and in 1943 grants Burma a nominal version of it. Yet Japanese officers keep the real power, seize rice and labor, and punish dissent harshly. The nationalist leader Aung San made exactly this journey: he trained with the Japanese, led a Burmese army beside them, then switched to the Allied side in March 1945. His choice shows a pattern across the region. People judged occupiers by what they did, not by their slogans, and the war weakened European empires even as it exposed Japan's own imperial aims. Level 8 follows that thread into decolonization.