Battle of Loos

The Battle of Loos was the largest British offensive mounted in 1915 on the Western Front during World War I. The first British use of poison gas occurred and the battle was the first mass engagement of New Army units. The British offensive was part of the attempt by the French 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. Casualties in the Herbstschlacht (Autumn Battle) were high on both sides.

• http://en.wikipedia.org/wiki/Battle of Loos