Adriatic: 2 Italian MAS boats penetrate Trieste, MAS9 (Lieutenant Rizzo) sinks Austrian battleship Wien, worst Austrian warship loss so far.
North Sea: Royal Navy Air Service seaplanes bomb Bruges docks and airfields near Ghent.
Belgium: Petain visits King Albert, ‘deplores the inefficiency of the British Command. The troops are excellent but they have been clumsily used. The Americans lack discipline and experience’.
Cambrai: British capture post east of Boursies (on Bapaume-Cambrai road).
Verdun: Unsuccessful German attack on Chaume Wood (and on December 15).
Russia: Lenin drafts outline peace programme for negotiations.
Ukraine: Red railway detachments defeat Kornilov north of Kharkov and near Belgorod on December 13.
Salonika: Clemenceau recalls Sarrail who leaves on December 22.