Timeline: Japanese actions during World War II
1937: Japan invades China and captures Nanking
1938: Japan opens the first wartime facility for "sexual comfort" in Nanking
1939: Japan establishes the "Unit 731" research laboratory for biological warfare in Harbin, China, and tests biological weapons on war prisoners (10,000 die)
1940: Italy, Germany and Japan sign the pact of the "axis"
1940: Japan bombs the Chinese city of Ningbo with fleas carrying the bubonic plague
1941: Japan attacks the USA fleet at Pearl Harbor
1941: Japan invades the Philippines and Thailand
1942: Japan invades the Dutch East Indies (Indonesia) and British India
1944: the USA drops 22,885 tons of bombs on the Tokyo-Kawasaki-Yokohama area
1945: the USA drops two atomic bombs on Hiroshima and Nagasaki and emperor Hirohito surrenders
1945: World War II ends and Japan is forced to retreat from the land it occupied; Nanking is liberated