World War I: Battle of Loos

Battle of Loos
British troops advance through the gas at the Battle of Loos. Public Domain

The Battle of Loos was fought September 25-October 14, 1915, during World War I (1914-1918). Seeking to end trench warfare and resume a war of movement, British and French forces planned joint offensives in Artois and Champagne for late 1915. Attacking on September 25, the assault marked the first time that the British Army deployed poison gas in large quantities. Lasting nearly three weeks, the Battle of Loos saw the British make some gains but at an extremely high cost. When the fighting ended in mid-October, British losses were around twice those suffered by the Germans.


Despite heavy fighting in the spring of 1915, the Western Front remained largely stagnant as Allied efforts in Artois failed and the German assault at the Second Battle of Ypres was turned back. Shifting his focus east, German Chief of Staff Erich von Falkenhayn issued orders for the construction of defenses in depth along the Western Front. This led to the creation of a three-mile deep system of trenches anchored by a front line and second line. As reinforcements arrived through the summer, the Allied commanders began planning for future action.

Reorganizing as additional troops became available, the British soon took over the front as far south as the Somme. As troops were shifted, General Joseph Joffre, the overall French commander, sought to renew the offensive in Artois during the fall along with an assault in Champagne. For what would become known as the Third Battle of Artois, the French intended to strike around Souchez while the British were requested to attack Loos. Responsibility for the British assault fell to General Sir Douglas Haig's First Army. Though Joffre was eager for an assault in the Loos area, Haig felt the ground was unfavorable (Map).

The British Plan

Expressing these concerns and others regarding a lack of heavy guns and shells to Field Marshal Sir John French, commander of the British Expeditionary Force, Haig was effectively rebuffed as the politics of the alliance required that the assault proceed. Reluctantly moving forward, he intended to attack along a six division front in the gap between Loos and the La Bassee Canal. The initial assault was to be conducted by three regular divisions (1st, 2nd, & 7th), two recently-raised "New Army" divisions (9th & 15th Scottish), and a Territorial division (47th), as well as to be preceded by a four-day bombardment.

Field Marshal Sir John French. Photograph Source: Public Domain

Once a breach was opened in the German lines, the 21st and 24th Divisions (both New Army) and cavalry would be sent in to exploit the opening and attack the second line of German defenses. While Haig wanted these divisions released and available for immediate use, French declined stating they would not be needed until the second day of the battle. As part of the initial attack, Haig intended to release 5,100 cylinders of chlorine gas towards the German lines. On September 21, the British began a four-day preliminary bombardment of the assault zone.

Battle of Loos

  • Conflict: World War I (1914-1918)
  • Dates: September 25-October 8, 1915
  • Armies and Commanders:
  • British
  • Field Marshal Sir John French
  • General Sir Douglas Haig
  • 6 divisions
  • Germans
  • Crown Prince Rupprecht
  • Sixth Army
  • Casualties:
  • British: 59,247
  • Germans: around 26,000

The Attack Begins

Around 5:50 a.m. on September 25, the chlorine gas was released and forty minutes later the British infantry began advancing. Leaving their trenches, the British found that the gas had not been effective and large clouds lingered between the lines. Due to the poor quality of British gas masks and breathing difficulties, the attackers suffered 2,632 gas casualties (7 deaths) as they moved forward. Despite this early failure, the British were able to achieve success in the south and quickly captured the village of Loos before pressing on towards Lens.

In other areas, the advance was slower as the weak preliminary bombardment had failed to clear the German barbed wire or seriously damage the defenders. As a result, losses mounted as German artillery and machine guns cut down the attackers. To the north of Loos, elements of the 7th and 9th Scottish succeeded in breaching the formidable Hohenzollern Redoubt. With his troops making progress, Haig requested that the 21st and 24th Divisions be released for immediate use. French granted this request and the two divisions began moving from their positions six miles behind the lines.

Corpse Field of Loos

Travel delays prevented the 21st and 24th from reaching the battlefield until that evening. Additional movement issues meant that they were not in position to assault the second line of German defenses until the afternoon of the September 26. In the meantime, the Germans raced reinforcements to the area, strengthening their defenses and mounting counterattacks against the British. Forming into ten assault columns, the 21st and 24th surprised the Germans when they began advancing without artillery cover on the afternoon of the 26th.

Gas over the Loos battlefield, 1915.
Gas attack on the Hohenzollern Redoubt, October 1915. Public Domain

Largely unaffected by the earlier fighting and bombardments, the German second line opened with a murderous mix of machine gun and rifle fire. Cut down in droves, the two new divisions lost over 50% of their strength in a matter of minutes. Aghast at the enemy losses, the Germans ceased fire and allowed the British survivors to retreat unmolested. Over the next several days, fighting continued with a focus on the area around the Hohenzollern Redoubt. By October 3, the Germans had re-taken much of the fortification. On October 8, the Germans launched a massive counterattack against the Loos position.

This was largely defeated by determined British resistance. As a result, the counter-offensive was halted that evening. Seeking to consolidate the Hohenzollern Redoubt position, the British planned a major attack for October 13. Preceded by another gas attack, the effort largely failed to achieve its objectives. With this setback, major operations came to a halt though sporadic fighting continued in the area which saw the Germans reclaim the Hohenzollern Redoubt.


The Battle of Loos saw the British make minor gains in exchange for around 50,000 casualties. German losses are estimated at around 25,000. Though some ground had been gained, the fighting at Loos proved a failure as the British were unable to break through the German lines. French forces elsewhere in Artois and Champagne met a similar fate. The setback at Loos helped contribute to the downfall of French as commander of the BEF. An inability to work with the French and active politicking by his officers led to his removal and replacement with Haig in December 1915.

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Hickman, Kennedy. "World War I: Battle of Loos." ThoughtCo, Jul. 31, 2021, Hickman, Kennedy. (2021, July 31). World War I: Battle of Loos. Retrieved from Hickman, Kennedy. "World War I: Battle of Loos." ThoughtCo. (accessed June 10, 2023).