- January 5th - Australians capture Bardia, Libya.
- January 22nd - British and Australians capture Torbruk.
- February 6th - British and Australians capture Benghazi.
- February 25th - British capture Mogadishu, Italian Somaliland.
- March 1st - Bulgaria joins Axis.
- March 25th - Yugoslavia signs Tripartite Pact.
- March 27th - Yogoslav government overthrown - leaves Pact.
- March 30th - German Afrika Korps begins offensive in N. Africa.
- April 4th - Germans capture Benghazi.
- April 6th - Germany invades Yugoslavia and Greece.
- April 10th - Germans take Zagreb.
- April 12th - Germans occupy Belgrade.
- April 13th - Soviets and Japanese sign neutrality pact.
- April 17th - Yugoslav army surrenders to Germans.
- April 22nd - Germans capture Thessalonika.
- April 27th - Germans capture Athens.
- April 28th - Germans take Sollum.
- May 15th - British re-capture Sollum and Halfaya.
- May 20th - German airborne invasion of Crete.
- May 31st - British forces in Crete defeated.
- June 8th - Allied forces invade Syria.
- June 22nd - Operation Barbarossa - Germany invades Soviet Union.
- June 22nd - Italy and Rumania declare war on Soviets.
- June 23rd - Hungary and Slovakia declare war on Soviets.
- June 26th - Finland declares war on Soviets.
- June 28th - German Army captures Minsk.
- July 15th - Germans capture Smolensk.
- August 16th - Germans capture Novogrod.
- September 5th - German army occupies Estonia.
- September 15th - Siege of Leningrad starts.
- September 19th - Kiev captured by Germans.
- October 16th - Soviet Union moves government to Kuibyshev.
- October 24th - Kharkov falls to Germans.
- November 3rd - Germans capture Kursk.
- November 22nd - Germans captue Rostov.
- November 25th - Germans attack Moscow.
- December 5th - Germans halt attack on Moscow.
- December 7th - Japanese attack on Pearl Harbour.
- December 7th - Japanese declare war on USA.
- December 7th - Japanese invade Siam and Malaya.
- December 8th - Allies (except Soviets) declare war on Japan.
- December 11th - Germany declares war on USA.
- December 25th - Japanese capture Hong Kong.
- December 25th - British Re-capture Benghazi.