Britain: Air defences finally told of Giant bomber, codenamed Bertie, after its eight raid.
Channel: New Dover Straits minefield claims first victim, coastal submarine UB-56 after Vice-Admiral Bacon advised to start flare and searchlight surface patrol along it.
Adriatic: 2 old Austrian battleships, 1 cruiser, 6 destroyers shell Italian Cortellazzo batteries again, but big ships withdrawn to Pola on December 20, 3 old battleships mothballed after December 28 to obtain personnel.
Piave: British artillery in action at Montello. Italian counter-attacks against Mts Rertica and Asolone fail to gain ground until fog and thick snow end operations on December 21.