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
Gas mask wearer to breathe the safer air found there. In addition, moist sponges were inserted at the end of the hoses in order to better filter the air. This was later modified to include its own air supply, leading to World War I era gas masks.<ref name="pbs.org/wgbh/theymadeamerica2"></ref><ref name="encyclopedia.com/topic/Garrett_Morgan2"></ref><ref name="biography.com/people/garrett-morgan2"></ref> The German army used poison gas for the first time against Allied troops at the Second Battle of Ypres, Belgium on 22 April 1915. As an immediate response was cotton wool wrapped in muslin issued to the troops by 1 May. This was followed by the Black Veil Respirator, invented by John