On August 23, 1914, at the Battle of Mons, General Alexander von Kluck's troops forced a British withdrawal. An excerpt from the article:
"The British Hold
At 5:30 AM on August 23, French again met with Haig and Smith-Dorrien and told them to strengthen the line along the canal and to prepare the canal bridges for demolition. In the early morning mist and rain, the Germans began appearing on the BEF's 20-mile front in increasing numbers. Shortly before 9:00 AM, German guns were in position north of the canal and opened fire on the BEF's positions. This was followed by an eight-battalion assault by infantry from IX Korps. Approaching the British lines between Obourg and Nimy, this attack was met by heavy fire form the BEF's veteran infantry. Special attention was paid to the salient formed by the loop in the canal as the Germans attempted to cross four bridges in the area.
Decimating the German ranks, the British maintained a such a high rate of fire with their Lee-Enfield rifles that the attackers believed they were facing machine guns. As von Kluck's men arrived in greater numbers, the attacks intensified forcing the British to consider falling back. On the north edge of Mons, a bitter fight continued between the Germans and the 4th Battalion, Royal Fusiliers around a swing bridge. Left open by the British, the Germans were able to cross when Private August Neiemeier jumped in the canal and closed the bridge.
Retreat
By afternoon, French was forced to order his men to begin falling back due to heavy pressure on his front and the appearance of the German 17th Division on his right flank. Around 3:00 PM, the salient and Mons were abandoned and elements of the BEF became engaged in rearguard actions along the line. In one situation a battalion of the Royal Munster Fusiliers held off nine German battalions and secured the safe withdrawal of their division. As night fell, the Germans halted their assault to reform their lines.
Though the BEF established new lines a short distance south, word arrived around 2:00 AM on August 24 that the French Fifth Army was in retreat to the east. With his flank exposed, French ordered a retreat south into France with the goal of establishing at line along the Valenciennes–Maubeuge road. Reaching this point after a series of sharp rearguard actions on the 24th, the British found that the French were still retreating. Left little choice, the BEF continued to move south as part of what became known as the Great Retreat (Map).
Aftermath
The Battle of Mons cost the British around 1,600 killed and wounded, including later WWII hero Bernard Montgomery. For the Germans, the capture of Mons proved costly as their losses numbered around 5,000 killed and wounded. Though a defeat, the stand of the BEF bought valuable time for Belgian and French forces to fall back in an attempt to form a new defensive line. The BEF's retreat ultimately lasted 14 days and ended near Paris (Map). The withdrawal ended with the Allied victory at the First Battle of the Marne in early September."