On This Day - 31 January 1917
Theatre definitions: Western Front comprises the Franco-German-Belgian front and any military action in Great Britain, Switzerland, Scandinavia and Holland. Eastern Front comprises the German-Russian, Austro-Russian and Austro-Romanian fronts. Southern Front comprises the Austro-Italian and Balkan (including Bulgaro-Romanian) fronts, and Dardanelles. Asiatic and Egyptian Theatres comprises Egypt, Tripoli, the Sudan, Asia Minor (including Transcaucasia), Arabia, Mesopotamia, Syria, Persia, Afghanistan, Turkestan, China, India, etc. Naval and Overseas Operations comprises operations on the seas (except where carried out in combination with troops on land) and in Colonial and Overseas theatres, America, etc. Political, etc. comprises political and internal events in all countries, including Notes, speeches, diplomatic, financial, economic and domestic matters. Source: Chronology of the War (1914-18, London; copyright expired)
Western Frontthe Ancre near Beaucourt and west of Serre German attacks fail.
Total of German prisoners taken by British in France during January is 1,228, including 27 officers.
East of Jakobeny Germans attack three times by night against previous lost positions, but are repulsed with heavy loss.
Naval and Overseas Operations
Germany declares to all neutrals "Unrestricted naval warfare", i.e. within the war zone, German submarines will sink both combatant and neutral shipping at sight from 1 February.
Germany announces that the traffic of British hospital ships between Great Britain, France and Belgium will no longer be tolerated. The false reason assigned is misuse of the Red Cross.