Start of World War II By trichards Period: Jan 1, 1939 to Dec 31, 1939 1939 Aug 25, 1939 Britain/Poland sign Mutual Assistance Treaty Sep 1, 1939 Germany Invades Poland Sep 3, 1939 Britain declares war on Germany Sep 5, 1939 U.S. declares Neutrality Sep 10, 1939 Canada declares War on Germany Radio Canada - broadcast Sep 17, 1939 Soviets invade Poland
