The Enigma code is deciphered by the intelligence group at Bletchley Park in England for the first time.
Another bombing of London, notable because Buckingham Palace is hit.
The US announces an oil embargo against "aggressors."
Warsaw's Jews are directed to move into the Warsaw ghetto.
The Invasion of Poland by Nazi Germany begins at 4:45 a.m. with the Luftwaffe attacking several targets in Poland.
The U.S. Neutrality Act is passed: the French and British may buy arms, but on a strictly cash basis. American isolationists find the act an "outrage."
Crucial British Cabinet meeting: Churchill wins a vote on continuing the war, in spite of vigorous arguments by Lord Halifax and Chamberlain.
Following a massive artillery bombardment, the Germans launch a major infantry assault on the center of Warsaw.
The United States, the United Kingdom, the Netherlands and New Zealand declare war on Japan
Germany and Italy declare war on the United States. The United States reciprocates and declares war on Germany and Italy.
Large German air-raids on London; St Paul's Cathedral is damaged.
The USA publicly declared neutrality.
Japan launches an attack on Pearl Harbor, declares war on the United States and the United Kingdom and invades Thailand and British Malaya and launches aerial attacks against Guam, Hong Kong, the Philippines, Shanghai, Singapore and Wake Island. Canada declares war on Japan.
United States President Franklin Delano Roosevelt signs the Lend Lease Act (now passed by the full Congress) allowing Britain, China, and other allied nations to purchase military equipment and to defer payment until after the war.
The USSR is expelled from the League of Nations in response to the Soviet invasion of Finland on November 30.
Portions of Poland are formally inducted into Germany; the first Jewish ghetto is established at Lublin
President Roosevelt wins a third term. The British see the event as promising of more help from the US.
Cardiff is bombed by the Luftwaffe for the first time.
Luftwaffe attacks on Wales, Scotland and Northern Ireland.