The Canadian infantry assembled in the trenches at midnight between August 14th and 15th. German artillery was being fired at the Canadian trenches. At 4:25 in the morning on August 15th, the Canadians started their attack on the German trenches. One minute later, the Germans followed up with a counter attack. After a struggle, the Canadians settled near the edge of Lens. At 8:15 the Germans began their counterattack, having to cross 1 kilometre of Canadian machine gun and rifle fire. The same thing happened during another counterattack at 12:45, with Germans being destroyed by the Canadian fire. The Germans attacked again at 13:15. This time they managed to cut the Canadian communication lines linked to the Canadian artillery. However, runners were able to send messages to the artillery telling them to open fire on the Germans. August 16th had a relatively quiet morning, however a massive German counterattack at 19:15 was unsuccessful and dealt the Germans 1651 casualties. On August 17th, Canadian infantry failed to take over some German-occupied land between the cities of Cité St Élisabeth and Lens. The Germans later decided to fire over 15000 sulphur mustard shells along with some diphosgene shells, giving 183 casualties to the Canadians. On the morning of August 18th, a Canadian line was penetrated by German troops using flamethrowers. On August 21st, the Germans began shelling the Canadians just before their attack at 4:35 in the morning. Later, Canadians forces fought the German troops hand-to-hand using bayonets. In the evening, three small Canadian groups all having under 20 men, reached their goal. Whilst the other Canadian forces reached theirs’ in the evening. Finally, they started bombing the German forces from their flank. The Canadians had captured Hill 70 and thus gained the high ground overlooking Lens. However, the Germans remained in Lens until their final retreat in 1918.