31 August

Western Front

 * Germans reach Givet.
 * French Army holds the line Aisne-La Vesle-Reims-Verdun.
 * Battle of the Grande Couronne of Nancy (31 August–11 September)

Eastern Front

 * East Prussia: Alexander Samsonov commits suicide during Russian rout; Paul von Rennenkampf forced to begin a retreat to the frontier.
 * Galicia: Austrian line broken near Halicz.