What happened December 1939 AD

Turing decided to tackle the particularly difficult problem of German naval Enigma "because no one else was doing anything about it and I could have it to myself". In December 1939, Turing solved the essential part of the naval indicator system, which was more complex than the indicator systems used by the other services.That same night, he also conceived of the idea of Banburismus, a sequential statistical technique to assist in breaking the naval Enigma.

Eisenhower returned to the United States in December 1939 and was assigned as commanding officer (CO) of the 1st Battalion, 15th Infantry Regiment at Fort Lewis, Washington, later becoming the regimental executive officer.

Soviet Union was expelled from the League of Nations.

They spent Christmas at Sandringham House before moving to Windsor Castle, just outside London, for much of the remainder of the war.