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
German Type U 151 submarine U 139 "U-cruisers", designed from the outset as military submarines. "Deutschland" made two successful commercial voyages before being commissioned into the Kaiserliche Marine on February 17, 1917 as "U-155". Max Valentiner commanded a Type U 151 U-boat, , and undertook the longest cruise in the war from 27 November 1917 to 15 April 1918, a total of 139 days. High-scoring Waldemar Kophamel also commanded a Type U 151 U-boat, in late summer and fall of 1917. Seven Type U 151 submarines were built, of which six were commissioned into the Kaiserliche Marine. German Type U 151 submarine Type U 151