The
Battle of the Frontiers was a series of
battles fought along the eastern frontier of
France and in southern
Belgium shortly after the outbreak of
World War I. The battles resolved the
military strategies of the French Chief of Staff General
Joseph Joffre with
Plan XVII and an offensive interpretation of the
German deployment plan by
Helmuth von Moltke the Younger. The German concentration on the right (northern) flank, to wheel through Belgium and attack the French in the rear, was delayed by the movement of General
Charles Lanrezac's Fifth Army towards the north-west to intercept them and the presence of the
British Expeditionary Force (BEF) on his left flank. The Franco-British were driven back by the Germans, who were able to invade northern France. French and British rearguard actions delayed the German advance, allowing the French time to transfer their forces to the west to defend
Paris, resulting in the
First Battle of the Marne.