Chemical weapons and the United Kingdom army against British and Canadian soldiers near Ypres, Belgium, in 1917 and later also against the French Second Army. The name Yprite comes from its usage by the German army near the town of Ypres. The Allies did not use mustard gas until November 1917 at Cambrai, France, after the armies had captured a stockpile of German mustard-gas shells. It took the British more than a year to develop their own mustard gas weapon, with production of the chemicals centred on Avonmouth Docks. (The only option available to the British was the Despretz–Niemann–Guthrie process). This was used first in September
Tanks in the German Army the Anglo-Canadian forces of the 21st Army Group; and the numerous battles to secure the town became collectively known as the Battle of Caen. US forces in the meantime, engaged mainly the "Panzer Lehr" Division, and the Panther tank proved to be most effective when fighting in open country and shooting at long range—its combination of superior armor and firepower allowed it to engage at distances from which the American M4 Shermans could not respond. The Tiger was first used in action on 23 September 1942 near Leningrad. Under pressure from Hitler, the tank was put into action months earlier