On December the 4th the 107th and 109th Brigades moved up from Lechelle and Bertincourt, halting in Havrincourt Wood for dinners _en route_. The 107th Brigade was disposed in old British trenches between Beaucamp and Villers-Plouich, the 109th in the old German front line north of the former, where it was in reserve to the 6th Division. The two Field Companies left behind, and the Pioneers, rejoined the Division, moving to a camp near Dessart Wood. Headquarters of the Division were established in an infantry camp at Sorel-le-Grand. That night the 108th Brigade relieved the 88th in the line, in the Couillet Valley. The next night the 109th Brigade followed, taking over the important plateau known as Welsh Ridge from the 182nd Brigade of the 61st Division. On this night G.H.Q. carried out a grave but inevitable decision. The success of the German attack on the southern face of the Bourlon-Noyelles-Masnières Salient had made that salient so narrow in proportion to its depth that its maintenance would be a constant source of attrition. A considerable portion of the ground here, including Bourlon Wood, Cantaing, Noyelles, Graincourt, and Marcoing, was evacuated, all dug-outs within the area being systematically destroyed. This withdrawal was to have an effect upon the relief to be carried out by the 36th Division. The new line, of which General Nugent assumed command on the relief of the 182nd Brigade, was curious and somewhat indeterminate as to exact position. It represented an acute salient, of which the nose pointed due east. Behind this ran, from south-west to north-east, the deep, densely-wooded Couillet Valley. At the south-west end was the ruined village of Villers-Plouich, at the north-east the little damaged village of Marcoing, captured by the British in the Cambrai battle, but now again in German hands. On either side of the Couillet Valley were the two ridges destined to become famous, Welsh Ridge on the south-east, and Highland Ridge on the north-west. Across these, at right angles to the Couillet Valley, ran the two Hindenburg Systems, which on Welsh Ridge drew to within two hundred yards of each other, forming a single system of defence. That fact proved how highly the men who had sited those trenches rated the importance of Welsh Ridge. To the British at this moment it was well-nigh as valuable as it had been to the enemy.