The Battle of Mons, 23 August 1914, was part of the wider Battle of the Frontiers of France (First World War). It was the first battle fought by the British Expeditionary Force since its arrival in France during the second week of August. On 22 August the five divisions of the BEF (four infantry and one cavalry) reached the Mons-Condé canal and took up positions along twenty miles of the canal. Sir John French, the commander of the BEF, had been expecting to join a French offensive into Belgium, but this plan had been based on a misunderstanding of the German plan. On 22 August the French had suffered a serious setback at the Sambre, when their Fifth Army had been attacked by the German Second and Third Armies.
During the night of 22 August French received a request to launch a counterattack against what was believed to be the right flank of the German army advancing through Belgium. This belief was mistaken. The German First Army, under General Alexander von Kluck, was advancing directly towards the British position – there was no open flank to attack. Fortunately French did not agree to the French plan, and instead simply promised to hold the line of the canal for 24 hours.
This was exactly what happened. On 23 August the First Army collided with the thin British line. 70,000 British soldiers with 300 guns faced as many as 160,000 Germans, supported by 600 guns. I Corps under General Douglas Haig was on the British right, II Corps under General Sir Horace Smith-Dorrien on the left.
Although they were badly outnumbered, the British did have two big advantages. Both came from the professional volunteer nature of the British army. Many members of the BEF were long service soldiers, with experience gained in Britain’s colonial wars, but most importantly of all in the Boer War. There the British regulars had performed badly against the Boers, who combined accurate rifle fire with a willingness to dig deep trenches. On the South Africa plains the British had suffered a series of defeats on the empty battlefield, and had learnt their lessons. The British regular soldier of 1914 was expected to be able to fire fifteen aimed shots per minute. At Mons the British rifle fire was so rapid and so accurate that many Germans believed they had been facing massed machine guns.
The second British advantage at Mons was their willingness to entrench. At Mons they found the ideal environment for a defensive battle. The canal ran through a mining area, and was thus lined with mine buildings and spoil heaps that provided a multitude of potential strong points. When the first Germans reached the canal on 22 August, the British were almost invisible.
The German attack on 23 August was badly organised. At first the Germans attacked as they arrived on the scene, allowing the British to defeat them piecemeal. A more organised German attack later in the day did see German forces capture a salient on the southern bank of the canal, but the first days fighting between the BEF and the German army had gone to the British.
That night Sir John French ordered the BEF to pull back a short distance to the south, and to create a new fortified line. He had every intention of resuming the fight on 24 August. However, to the east the French were still retreating. A dangerous gap was beginning to open up between the BEF and the French Fifth Army, and so on the morning of 24 August French was forced to order a general retreat. This retreat would last for two weeks, and would cost the BEF many more casualties than had fallen at Mons.
British losses during the battle were around 1,600. German losses were not officially calculated but are generally accepted to have been between 3,000 and 5,000. The problem for the BEF was that the Germans could better afford to lose 5,000 conscripts than the British could afford to lose 1,600 of their precious regulars. By the end of the year the fighting at Mons, Le Cateau and in the First Battle of Ypres came close to wiping out the pre-war British army.