Though the advance of Birdwood's Army was comparatively bloodless there was still some obstinate fighting in the north, and the divisions which forced the Lys had by no means a holiday task. This operation was carried out on October 20 and 21, and owing to some delay on the part of the French Seventh Corps in getting into position the flank of the Thirty-sixth Ulster Division was exposed to enfilade fire which caused great loss. As the Ulsters advanced across the river they had to throw back a defensive flank 6000 yards deep before evening of the 21st. On the 22nd the Germans were still fighting stoutly, and delivered at least one {291} dangerous counter-attack by storm-troops, while on the 25th they brought a new division, the Twenty-third Reserve, an old opponent of early Ypres days, into the line, and held their ground well. There were changes in the British fighting line also, as the Thirty-first relieved the Twenty-ninth, while the Thirty-fourth, coming from the south, took the place of the Ulsters. These two divisions attacked once more on October 31, the Thirty-first surrounding Caster while the Thirty-fourth captured Anseghem, the 8th Scottish Rifles forcing their way into the town, and joining up with the French at Winterkan. That evening the enemy retired across the Escaut, and the line was definitely made good. The bridges over the river had been destroyed, but the French were advancing rapidly from the north, and on November 2 had reached Driesen and Peterghem. They then extended south and took over the whole front of the Second Corps, joining up with the left of the Nineteenth Corps. The Second Corps drew out from its last battle, having since the advance began captured 7500 prisoners and 150 guns, at a loss to itself of 11,000 casualties. At this period the operations of the north may be said to have reached their term.