The 1st Division spent the winter of 1914–15 training in England, and was sent to France in February 1915. After a period of indoctrination about the realities of trench warfare, the Canadians took control of a section of trench in the Ypres Salient on April 17, 1915. Only five days later, on Hughes' 34th birthday, the Germans used poison gas for the first time on the Western Front, sending clouds of chlorine wafting over the Allied trenches. French colonial troops on the Canadians' left flank broke, leaving an enormous hole in the Allied line.