A clash between Japanese and Chinese troops near Beijing begins the full-scale Second Sino-Japanese War (1937–1945).
After capturing Nanjing, the Imperial Japanese Army kills large numbers of Chinese prisoners and civilians over several weeks.
Soviet and Mongolian forces under Georgy Zhukov defeat the Japanese on the Mongolian–Manchurian border.
Germany invades Poland, starting the deadliest conflict in human history, which ends with Japan's formal surrender on 2 September 1945.
The Chinese Red Army retreats thousands of kilometres from Nationalist forces; Mao Zedong emerges as leader during the march.
Japanese forces attack Lạng Sơn and land near Haiphong, compelling the French administration to accept Japanese bases in Tonkin.
The Imperial Japanese Navy launches a surprise attack on the US naval base at Pearl Harbor, Hawaii, bringing the United States into World War II.