Quick Facts
Date:
August 23, 1914
Location:
Belgium
Mons
Context:
World War I

Battle of Mons, (August 23, 1914) engagement between the British Expeditionary Force (BEF) and the German army at Mons, Belgium, during the Battle of the Frontiers in the opening weeks of World War I. The German victory forced the BEF into a retreat that was not checked until the First Battle of the Marne.

Britain declared war on Germany on August 4, 1914, and the lead elements of the BEF began arriving in France just days later. The British, after concentrating near Maubeuge, France, had moved up to Mons on August 22, ready to advance farther into Belgium as part of an offensive by the Allied left wing. BEF commander Field Marshal Sir John French soon learned that the French Fifth Army under Charles Lanrezac had been checked on August 21 and deprived of the crossing of the Sambre River. Although thus placed in an exposed forward position, French agreed to stand at Mons with his two corps to cover Lanrezac’s left.

The British line was shaped somewhat like a broad arrow with its tip at Mons. The British II and I Corps were practically at right angles to each other and faced, generally speaking, north and northeast, respectively. As matters turned out, the German attack on the BEF was directed almost entirely against Gen. Sir Horace Smith-Dorrien’s II Corps on the British left, where the situation was not unfavourable for the British. A canal that looped north of Mons provided a valuable defensive line, while the terrain on the opposite side held numerous difficulties for the attackers. Muddy ditches and barbed-wire fences impeded movement, but clumps of trees and bushes provided valuable cover and were of service for the enemy’s machine guns. South of the canal, the crests of the high ground afforded the British useful sites for artillery, but the slag heaps of the numerous mines limited observation to some extent. The loop in the canal also constituted an obvious salient, and Smith-Dorrien had prepared another, more defensible, line linking the villages of Frameries and Boussu.

When day broke on August 23, the British force of about 75,000 men and 300 guns was opposed by some 150,000 men and 600 guns of the German First Army under Gen. Alexander von Kluck. The German First Army had been ordered to shift its direction of attack from southwest to south, toward Mons, but Kluck was ignorant of the position of the British force. Indeed, there was a delay early in the day caused by a report that Allied troops, perhaps British, were detraining in force at Tournai, some 25 miles (40 km) northwest of Mons. The town was actually held by two French territorial battalions, but Kluck halted three corps to deal with the possible threat to his right flank. By late morning, Kluck had realized that the British were in strength on the canal and that the troops at Tournai, now known to be French, had retired toward Lille.

Once Kluck had grasped the real state of affairs, his plan appears to have been to envelop both the British flanks while bombarding the front heavily with his guns. The bulk of the day’s fighting thus fell upon the salient formed by the canal loop around Mons, but the envelopment of the British left did not succeed, in part because of the delay caused by the phantom British force in Tournai. The battle opened in earnest about 10:30 am with a bombardment by German batteries located on high ground northeast of the Mons salient. From that time onward the guns were gradually extended westward as battery after battery came into action against the British II Corps. By the early afternoon, the Germans had established a great superiority of artillery, but their advance was slowed by murderously accurate rifle fire by the British defenders. In addition, British guns, though vastly outnumbered by the German artillery, gave most effective support.

German superiority in numbers finally overcame British resistance, and the British were gradually forced back east and southeast of Mons. The Germans were cautious about pushing into the town, however, and it was not until after 7:00 pm that they entered Mons. The collapse of the Mons salient inevitably led to a slight withdrawal by the remainder of the II Corps, and by nightfall a new line had been established some 3 miles (5 km) from the canal.

During the late afternoon and evening, French had been receiving disquieting news as to the situation of the French army on his right. About 11:30 pm, he received a telegram confirming that the Belgian fortress of Namur had fallen during the day and that Lanrezac’s Fifth Army was withdrawing after fierce attacks by Gen. Karl von Bülow’s Second Army. In these circumstances not only was the planned Allied offensive out of the question, but also the British line was now untenable. On August 24 the British began to fall back in conformity with their allies, from the Belgian frontier toward the Marne. The decision was made not a moment too soon, as the remainder of the German First Army was marching still farther westward in an attempt to envelop the open British left flank.

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The battle was a strategic victory for Germany, as the British stand at Mons slowed, but did not stop, the advance of the German army into France. The British suffered some 1,600 casualties, with losses concentrated especially in those units which occupied the canal salient. As many as 5,000 Germans were killed or wounded in the one-day engagement. These totals were comparable to 19th-century battles between European powers, such as those that occurred during the Crimean War (1853–56) or the Franco-German War (1870–71), and gave little indication of the bloodshed that would become commonplace on the Western Front.

The Editors of Encyclopaedia Britannica This article was most recently revised and updated by Michael Ray.

Western Front, major theatre of World War I. The name refers to the western side of territory under the control of Germany, which was also fighting on its eastern flank for most of the conflict. The struggle between the Allied and Central armies at the Western Front largely determined the course of the war.

For all the bloody combat that occurred on the Western Front between 1914 and 1918, the front line remained largely static. At its greatest extent, the front ran some 440 miles (700 km) from the Belgian coast at Nieuwpoort, through France, and all the way to the border of Switzerland, just south of the Alsatian village of Pfetterhouse. The contours of the line reflected the extent of German success during the war. In a sequence of attacks that began on August 2, 1914, the Germans executed a modified version of the Schlieffen Plan, a battle plan that was conceived to allow Germany to effectively prosecute a two-front war. German forces invaded France through Belgium, pushing the French army and the British Expeditionary Force back to within just 30 miles (48 km) of Paris. Simultaneously, Germany repelled an attempt by the French to seize territory in Alsace-Lorraine; Germany had claimed that historically French region as spoils of the Franco-German War in 1871. However, the First Battle of the Marne (September 6–12) rolled back Germany’s gains to just north of the Aisne River, where the opposing forces deadlocked. The First Battle of Ypres (October 19–November 22) did nothing to break the impasse; the front would shift no more than 50 miles (80 km) from that position until March 1918, eight months before the war’s end.

The Western Front became so fixed primarily because of a lopsided revolution in military tactics and technology. Simply put, advances in offensive warfare had not developed at the same rate as those in defensive warfare. In the early years of World War I, a force could protect itself with barbed wire, stationary machine guns, and rapid-fire artillery, but it could attack only with infantry armed with bolt-action rifles. This lack of parity between an attacker and a defender meant that new offensives rarely succeeded and almost always resulted in enormous casualties. The war in the west therefore settled into a prolonged stretch of trench warfare in which neither side could gain a clear advantage.

On April 22, 1915, German forces in Flanders attempted to break the impasse with a deadly and terrible new weapon. The French lines at Ypres were shattered when the Germans discharged nearly 200 tons (180,000 kg) of chlorine gas into the Allied trenches. The Germans failed to capitalize on the initial shock of the war’s first chemical weapon attack, however, and by the following night, their gains had been largely reversed.

Allied forces on the Western Front and the German army both endeavoured to end the standoff with new offensives in 1916. The Allies sought to overwhelm German forces with their combined numbers at the river Somme, but the Germans struck first in the region of Verdun, forcing the Allies to alter their plans. The upshot was that each side distracted the other from its goals, causing both offensives to fail. The Battle of Verdun lasted from February 21 to December 18. The First Battle of the Somme carried on from July 1 to November 13.

On April 16, 1917, the Allies tried again. Brashly claiming that he would end the war within 48 hours, the French army’s commander in chief, Robert Nivelle, launched 1.2 million men at the German fortifications beyond the Aisne River. The Nivelle Offensive, as it was later named, was such a disaster that many French soldiers mutinied. Nivelle himself was sacked on May 15, replaced by Philippe Pétain.

The British attempted to penetrate German territory in 1917 with three campaigns of their own in Flanders, starting on June 7. The ensuing Battle of Messines raged for one week and earned the British a minor victory. The Battle of Passchendaele (also called Third Battle of Ypres; July 31–November 6, 1917) is still a controversial one among historians. The British again advanced, ever so slightly, but the stunning loss of life that occurred in the fighting has made the choice to wage it a difficult one to defend. A total of nearly half a million casualties were suffered by the armies on both sides, and all the ground that had been gained by the Allies was evacuated the following year.

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The third British assault, on November 20, is looked upon much more favourably, for, although it did not result in much territorial gain, its success suggested new strategies for winning the war. The British use of tanks—new weapons of war that the Allies had begun developing in early 1915—to punch through enemy lines at the Battle of Cambrai (November 20–early December) gave the Allies a literal and figurative breakthrough. The use of tanks combined with other new advances, such as the use of “creeping” artillery barrages to cover troops’ progress across no-man’s-land, made true victories seem possible again.

In the east the troops of the Russian army had, in the words of Vladimir Lenin, “voted for peace with their legs,” and the representatives of the nascent Soviet state forged a separate peace with Germany. Freed to focus their efforts against the Allies in the west and eager to act before the United States could bring to bear its full military might, in 1918 a weary German army set in motion one last series of operations from March 21 to July 18. Alternately referred to as the Kaiser’s Battle or the Ludendorff Offensive (after its architect Erich Ludendorff), the assault took the German army once more to within shelling distance of Paris. But the Allies’ tanks again proved their mettle at the Second Battle of the Marne (July 15–18), stopping the German army in its tracks by smashing through its right flank.

The Allies’ counteroffensive brought an end to the war. In a campaign now remembered as the Hundred Days’ Offensive, the Allies—now buttressed with extensive reinforcements from the United States—won a chain of decisive victories, beginning with the Battle of Amiens (August 8–11). The German lines were broken, their divisions sent into retreat. Simultaneously, a revolution broke out in Germany, putting a new government in power that wanted peace. The Armistice of Compiègne was signed on November 11, 1918, bringing an end to World War I.

Adam Volle