The Gas Attack at Hulluch was an engagement in World War I from 27–29 April 1916, between divisions of the II Bavarian Corps and divisions of the British I Corps. Just before dawn on 27 April the 16th Division and part of the 15th Division were subjected to a German cloud gas attack, near the German-held village of Hulluch, a mile north of Loos. The gas cloud and artillery bombardment were followed by raiding parties, which made temporary lodgements in the British lines. Two days later another gas attack was launched, which blew back over the German lines and caused a large number of German casualties, which were increased by British troops firing at German soldiers as they fled in the open. The German gas was a mixture of chlorine and phosgene, which was of sufficient concentration to pen