Battle of Mons

The Battle of Mons, or the First Battle of Mons to differentiate it from another battle later in the war, was the first big engagement of the British Expeditionary Force (BEF) in the First World War. It was a subsidiary action of the Battle of the Frontiers, in which the Allies clashed with the German Army on the French–German frontier. At Mons, the British Army attempted to hold the line of the Mons–Condé Canal against the advancing German 1st Army. Although the British fought well and inflicted disproportionate casualties on the numerically superior Germans, they were forced to retreat due to being outnumbered and the sudden retreat of the French Fifth Army (General Charles Lanrezac) which exposed the British right flank. Though initially planned as a simple tactical withdrawal and executed in good order, the British retreat from Mons lasted for two weeks and took the BEF to the outskirts of Paris, before it counter-attacked in concert with the French, at the First Battle of the Marne.

Britain declared war on Germany on 4 August 1914 and on 9 August, the BEF began embarking for France. Unlike many Continental armies, the BEF in 1914 was small. At the beginning of the war, the German and French armies numbered well over a million men each, divided into eight and five field armies respectively; the BEF had c. 80,000 troops in two corps of long-service volunteers and reservists. The BEF was probably the best trained and most experienced of the European armies of 1914. British training emphasised rapid-fire marksmanship and the average British soldier was able to hit a man-sized target fifteen times a minute, at a range of 300 yd (270 m) with his Lee–Enfield rifle. This ability to generate a high volume of accurate rifle-fire played an important role in the BEF's battles of 1914.

The Battle of Mons took place during the Battle of the Frontiers, in which the advancing German armies clashed with the advancing Allied armies along the Franco–Belgian and Franco–German borders. The BEF was stationed on the left of the French line, which stretched from Alsace-Lorraine in the east to Mons and Charleroi in southern Belgium. The British position on the French flank meant that it stood in the path of the German 1st Army, the outermost wing of the massive "right hook" intended by the German deployment plan, a combination of the Aufmarsch I West and Aufmarsch II West plans, to pursue the Allied armies after defeating them on the frontier and force them to abandon northern France and Belgium or risk destruction.

The British reached Mons on 22 August. In the afternoon a message arrived from General Charles Lanrezac, addressed to Field Marshal Sir John French requesting the BEF to turn right to attack von Bülow's advancing flank. The Fifth Army, on the right of the BEF, was engaged with the German 2nd Army and the 3rd Army at the Battle of Charleroi. French refused, instead agreeing to hold the line of the Condé–Mons–Charleroi Canal for twenty-four hours, to prevent the 1st Army from threatening the French left flank. The British spent the day digging in along the canal.

At the Battle of Mons the BEF had some 80,000 men, comprising the Cavalry Division, the independent 5th Cavalry Brigade and two corps, each with two infantry divisions. I Corps (Sir Douglas Haig) was composed of the 1st Division and 2nd Division. II Corps (Sir Horace Smith-Dorrien) comprised the 3rd Division and 5th Division. Each division had 18,073 men and 5,592 horses, in three brigades of four battalions. Each division had twenty-four Vickers machine guns (two per battalion) and three field artillery brigades with fifty-four 18-pounder guns, one field howitzer brigade of eighteen 4.5-inch howitzers and a heavy artillery battery of four 60-pounder guns.

II Corps, on the left of the British line, occupied defensive positions along the Mons–Condé Canal, while I Corps was positioned almost at a right angle away from the canal, along the Mons–Beaumont road (see map). I Corps was deployed in this manner to protect the right flank of the BEF in case the French were forced to retreat from their position at Charleroi. I Corps did not line the canal, which meant that it was little involved in the battle and the German attack was faced mostly by II Corps. The dominant geographical feature of the battlefield, was a loop in the canal, jutting outwards from Mons towards the village of Nimy. This loop formed a small salient which was difficult to defend and formed the focus of the battle.

The first contact between the two armies occurred on 21 August, when a British bicycle reconnaissance unit encountered a German force near Obourg and Private John Parr became the first British soldier to be killed in the war. At 6:30 a.m. on 22 August the 4th Royal Irish Dragoons sent two officers' patrols from Obourg northwards towards Soignies and one drove off a German outpost, the first occasion that British troops fired on Germans. A troop advanced later and engaged German cavalry advancing south from Soignies towards Mons, repulsing it near Casteau and began a pursuit until stopped by German return-fire. Three to four German cavalry were killed and three taken prisoner from the 4th Cuirassiers of the 9th Cavalry Division. That day, having used British reconnaissance aircraft along with Lanrezac's messaging to his army staff, the BEF's chief of intelligence, Colonel George Macdonogh, warned French that three German corps were advancing towards the BEF. French chose to ignore these claims, instead proposing to advance towards Soignies.

Advancing towards the British was the German 1st Army, commanded by Alexander von Kluck. The 1st Army was composed of four active corps, II Corps (Lieutenant-General Alexander von Linsingen), III Corps, IV Corps (Lieutenant-General Ewald von Lochow) and IX Corps (Lieutenant-General Ferdinand von Quast) and three reserve corps, III Reserve Corps (Lieutenant-General Hans von Beseler), IV Reserve Corps (Lieutenant-General Hans von Gronau) and IX Reserve Corps (Lieutenant-General Max von Boehn), although only the active corps took part in the fighting at Mons. German corps had two divisions each, with attendant cavalry and artillery. The 1st Army had the greatest offensive power of the German armies, with a density of c. 18,000 men per 1 mi (1.6 km) of front, or about ten per 3 ft 3 in (1 m).