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
Action of 25 September 1917 the night. An intelligence summary of the Second Army assessed the German artillery in support of the of 25 September, to have been the greatest concentration of artillery on a German divisional sector ever known and was nearly four times the usual quantity for a division. The attacking battalions had assembled during the night of covered by parties of the line-holding battalions opposite the 33rd Division. The great mass of German artillery began a bombardment at but fell short and German infantry fired red flares to signal to the German artillery that they were falling short, especially on the III