From Berlin… Hitler issues Directive 21. Its message is simple: “The German Armed Forces must be prepared, even before the conclusion of the war against England, to crush Soviet Russia in a rapid campaign.” The projected operation is given the code name Barbarossa. Hitler has modified the draft plans prepared by the army in one important respect. Although three lines of attack are still suggested, Hitler's scheme reduces the importance which has been laid on the advance to Moscow. He suggests that after the first battles the center group should swing north to help clear the Baltic States and Leningrad before moving on the capital. The preparations are to be ready by May 15, 1940.

In the Mediterranean… The British submarine Triton is sunk by an Italian tropedo boat in the Straits of Otranto. Valona in Albania is shelled by the British battleships Valiant and Warspite (during the night of December 18-19). The Italians are also active in support of their armies in Albania with Lukova, just north of the Corfu Channel being shelled.

In Britain… A total of 10,969 people evacuated from Gibraltar have now arrived.