Dates when countries entered WW2 timeline

Period: Jul 7, 1937 to Sep 9, 1945

Second Sino-Japanese war begins between Japan and China
Period: Sep 3, 1939 to Sep 2, 1945

New Zealand, Britain, France, India, Australia and South Africa enter WW2 on the allies
Period: Sep 10, 1939 to Sep 2, 1945

Canada enters WW2 on the allies
Period: Jun 10, 1940 to Sep 8, 1943

Italy enters WW2 on the Axis Power
Period: Jun 22, 1941 to Sep 2, 1945

Soviet Union enters WW2
Period: Dec 8, 1941 to Sep 2, 1945

USA enters WW2 on the allies
Period: Oct 13, 1943 to Sep 2, 1945

Italy declares war on Germany, enters Allied side

Second Sino-Japanese war begins between Japan and China