To coordinate with Marshal Joffre's offensive in Champagne, Haig's British 1st Army and the French 10th Army under Gen. Dubail attacked von Falkenhayn's positions in Artois.
The British moved against positions around La Bassée Canal and the town of Loos while the French assaulted Vimy Ridge. Both attacks made progress, biting deep into the German 2nd and 3rd trench lines until lack of reserves slowed progress and effective counter-attacks drove them back.
This was the first use of poison gas by the British.

British & French Armies

Number engaged :

n/a

Casualties :

170,000

German Army

Number engaged :

n/a

Casualties :

165,000