Battle of Loos

The Battle of Loos was a World War I battle that took place from 25 September – 13 October 1915 in France on the Western Front, during the First World War. It was the biggest British attack of 1915, the first time that the British used poison gas and the first mass engagement of New Army units. The French and British tried to break through the German defences in Artois and Champagne and restore a war of movement. Despite improved methods, more ammunition and better equipment, the Franco-British attacks were contained by the German armies, except for local losses of ground. British casualties at Loos were about twice as high as German losses.

Strategic developments
The battle was the British part of the Third Battle of Artois, an Anglo-French offensive (known to the Germans as the Herbstschlacht (Autumn Battle). Field Marshal Sir John French and Haig (GOC First Army), regarded the ground south of La Bassée Canal, which was overlooked by German-held slag heaps and colliery towers, as unsuitable for an attack, particularly given the discovery in July, that the Germans were building a second defensive position behind the front position. At the Frévent Conference on 27 July, Field Marshal French failed to persuade Ferdinand Foch that an attack further north offered greater prospects for success. The debate continued into August with Joffre siding with Foch and the commanders being over-ruled by Herbert Kitchener, the British Secretary of State for War, on 21 August. On 3 May, the British decided upon use of poison gas in military operations in France. At a conference on 6 September, Haig announced to his subordinates that extensive use of chlorine gas might facilitate success despite the terrain, if the French and British were able to keep the attack secret and advance on a line towards Douai and Valenciennes.

British offensive preparations
The battle was the third time that specialist Royal Engineer tunnelling companies, were used to tunnel under no-man's-land, to plant mines under the parapets of the German front line trenches, to be detonated at zero hour.