Between August 10 and August 20, 1917, they were attacked in turn by six German divisions, each being shattered by the Canadians' dogged courage and amazing fighting power. These were the Seventh, Eighth, the Eleventh Reserve, the 220th and the First Guards Reserve Division. Besides those five divisions it was known that portions at least of the 185th Division and of the Sixth Reserve Division had also been engaged.
It was conservatively estimated by military observers of the struggle here that the German strength used at Lens was upwards of 50,000 men, and their losses were estimated at between 12,000 and 15,000 men.
At an early hour in the morning of August 20, 1917, the Canadians made a trench raid on the German front northwest of Avlon, where heavy fighting ensued. This front was strongly fortified by the Germans as protection for an important mining suburb southeast of Lens, and it was here that they had set up the guns withdrawn after the Canadian advance two days before. Here the hand-to-hand fighting was fierce and deadly, the Germans fighting with desperate courage, but the Canadians got the upper hand by slow degrees, and after inflicting heavy casualties took some prisoners and retired to their positions.
Early in the morning of the following day the forces from Canada again struck hard, attacking German trenches west and northwest of Lens. The battle raged throughout the day and far into the night. The Canadians advanced against strong opposition, using bomb and bayonet freely, winning important enemy positions to the northwest and southwest of the center of the city. It appears that the Germans had massed strong forces for a counterattack at daybreak against the newly won Canadian positions, and had already begun their forward push when they encountered the Canadians rushing across no-man's-land. Owing to a dense mist that prevailed at the time, the Germans did not see them until the foe fell upon them with bomb and bayonet.
This dramatic surprise for the Germans seemed to have had a chilling effect on their fighting spirit. They retreated in wild haste to the trenches they had left, despite the frenzied attempts of their officers to rally them. Close on their heels dashed the Canadians, and mounting the parapets showered bombs among the other troops that had gathered for the attack. As the Germans fled for the communication trenches the Canadians leaped among them, and with bomb and bayonet killed a great number.