The Second Battle of Ypres marked the Canadians’ first major engagement of the war. On 22 April 1915, two Canadian brigades were in the front lines when the Germans released gas against the French 45th Division to the Canadians’ left. Most of the gas missed the Canadians, but the French retreat exposed the Canadian’s left flank. On the 24th they faced a direct chlorine gas attack. The Canadians counterattacked to stall the German advance, and then slowly gave ground, buying time for British troops to be rushed forward. The Canadian Division’s trial-by-fire at Ypres earned them a reputation as tough and dependable troops, but they suffered some 6,000 casualties over the four-day battle.