13 September

Western Front

 * Allies recover Soissons and force the passage of the Aisne there.
 * Amiens recovered by the French.
 * Germans begin to drive the Belgians back into Antwerp; Battle along line Aerschot-Malines.

Eastern Front

 * East Prussia: Russians turn on their pursuers and defeat them at Sredniki near the Niemen.

Southern Front

 * Serbians and Austrians fighting in both Serbia and Syrmia.

Asiatic and Egyptian Theatres

 * Tsing-tau: Japanese capture the railway at Kiao-chau town.

Naval and Overseas Operations

 * Solomon Islands: Australian troops capture Bougainville.
 * The Hela, German cruiser, sunk by British submarine E9.

Political

 * Germany: Herr von Bethmann-Hollweg's reply to Mr. Asquith's Guildhall speech of 4 September published.