January 1: United States and Philippines troops fight the Battle of Bataan against Japanese forces. United Nations Declaration signed by China, UK, USA, and USSR in they agreed "not to make any separate peace with the Axis powers".

January 2: Manila is captured by Japanese forces. All defending soldiers in Manila are killed.

January 7: The siege of the Bataan Peninsula begins.

January 11: Dutch East Indies campaign: Japan declares war on the Netherlands and invades the Dutch East Indies. - Battle of Malaya: The Japanese capture Kuala Lumpur.

January 13: Sikorsky R-4 first flies, in the United States; it will become the first mass-produced helicopter. - Heinkel test pilot Helmut Schenk becomes the first person to escape from a stricken aircraft with an ejection seat.

January 16: Actress Carole Lombard and her mother are among those killed in a plane crash near Las Vegas, Nevada, while returning from a tour to promote the sale of war bonds.

January 17: Muhammad Ali is born in Louisville, Ky.

January 19: Japanese forces invade Burma. - Establishment of United States VIII Bomber Command, later to become the Eighth Air Force, in Savannah, Georgia.

January 20: Nazis at the Wannsee conference in Berlin decide that the "final solution to the Jewish problem" is relocation, and later extermination.

January 21: Erwin Rommel launches his new offensive in Cyrenaica.

January 23: The Battle of Rabaul begins.

January 25: Thailand declares war on the United States and United Kingdom.

January 26: The first American forces arrive in Europe, landing in Northern Ireland.

January 31: Battle of Malaya: The last organized Allied forces leave British Malaya, ending the 54-day campaign, and the Johor-Singapore Causeway is severed. (source: Wikipedia)