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
German Type U 93 submarine German Type U 93 submarine Type 93 was a class of U-boats built during World War I by the Kaiserliche Marine. Type 93 U-boats carried 16 torpedoes and had various arrangements of deck guns. As with the type 81 and 87, some had only one SK L/30 deck gun while others had a single SK L/45 gun and some were initially equipped with both. In 1917 some of the boats were refitted with a single 10.5 cm gun and 220 rounds. These boats carried a crew of 39 and had excellent seagoing abilities with a cruising range of around .