The Battle of the Mons marked the inaugural engagement of the British Expeditionary Force, marking the first time British troops had fought in Europe since the Crimean War in 1854. The primary objective of the British forces was to halt or impede the German advance. Despite their numerical inferiority, the British Expeditionary Force possessed a significant advantage in terms of professionalism and training. Comprising a Cavalry Division, Cavalry Brigade, and two infantry divisions, the British troops were highly skilled and disciplined. In contrast, the German forces, led by the 1st Army, were considerably larger, comprising four active corps and three reserve corps, each with two divisions. The 1st Army was poised to confront the British forces on the battlefield.

The British established defensive positions along the Mons-Conde Canal and at a right angle along the Mons-Beaumont road. On August 21, 1914, the initial contact occurred between the British troops and the advancing German troops. On August 23, the Germans launched a sustained attack on the British lines. The initial assault was unsuccessful, and the Germans were compelled to withdraw. Their second assault was more successful, ultimately forcing the British troops back from their advanced positions. The British withdrew to their secondary positions, only to discover that the French Fifth Army was retreating. The British forces were compelled to retreat in a orderly manner while engaging the Germans, the most challenging military maneuver. Despite heavy casualties, the British army managed to disengage from the line and initiate what became known as the Great Retreat. The British coast suffered 1,800 casualties in the battle, while the German forces had 2,145 dead and over 4,000 wounded. Despite being outnumbered 3 to 1, the British army held off the Germans for 48 hours before orderly withdrawing. While the tactical outcome of the battle was a German victory, as their forces advanced deep into France afterward, the Germans did not advance as rapidly as anticipated due to the fighting withdrawal of the British troops.