The battered German destroyer V69 in the Dutch port of Ymuiden Harbour after action with Harwich Flotilla in the North Sea, 23 January 1917. Image courtesy Imperial War Museum © IWM (Q 48422).
- The Harwich Flotilla clashes with German 6th Torpedo-Boat Flotilla in the North Sea; the destroyer HMS Simoom is torpedoed and damaged by SMS S-50. Her 81 crew are rescued by HMS Morris and she is scuttled by HMS Nimrod.
- German troops on the Eastern Front launch a counter-offensive between Lake Babit and Tirul Marsh; as a consequence Russian soldiers lose much of their recently captured ground.
- Bulgarian troops near Tulcea are driven back across the Danube River
