British war crimes September 1915 and continued their usage for the remainder of the war. This was done in retaliation for the use of chlorine by Imperial German Army the preceding April. Following the Imperial German Army's use of poison gas at Ypres, the commander of II Corps, Lieutenant General Sir Charles Ferguson, had said of poison gas: Mustard gas was first used effectively in World War I by the German army against British and Canadian soldiers near Ypres, Belgium, in 1917 and later also against the French Second Army. The name "Yperite" comes from its usage by the German army near the
Tanks in the German Army some areas. Twenty of these tanks were produced, and the first of these were ready in October 1917. The A7V was first used at St Quentin on 21 March 1918. Although some of its features, such as the sprung tracks and the thicker armour, made it better than British tanks at that time, the A7V was less successful as a battle vehicle. The main problems concerned its mechanical reliability and the difficulty it encountered crossing enemy trenches. By the time of the arrival of the Sturmpanzerwagen, the Germans had already successfully developed their own brand of armor-piercing projectile as well.