The relief of the 60th brigade headquarters had not been completed when the Germans began their counter-attack. After attacking the 12th and 55th Divisions on the right (south) flank at 07:00 hrs, the division was shelled with smoke, mustard gas and high explosive half an hour later. Aided by a thick mist in the valleys and by air support elsewhere, the Germans attacked the 20th Division's front and overwhelmed the outposts, some of which were in any case out of sight of the main line due to the convex slope of the spur north west of the canal. As the attack reached the main line the Germans also appeared on the division's right rear flank, having passed through the 12th Division's lines. With communications cut the reserve battalions had no sooner heard of the attack than they were subject to it, the headquarters and two companies of the 10th R.B. being overrun in this manner. The divisional and brigade machine gun companies also lost many of their guns and men, only a few men of the 217th MG company, north of Lateau Wood, escaping from the assault. The 83rd and 84th engineer companies were also swept up in the fighting, with the commanding officer of the 84th company assuming command of the 61st Brigade when its senior officers were killed. Two companies of the pioneers (11th D.L.I.) were in action at the northern end of Welsh Ridge the other two behind Gouzeaucourt. The remains of the two brigades fell back onto the slopes of Welsh Ridge. The division's artillery was also directly attacked, after the infantry had retreated through the 92nd Brigade's position, the artillery was firing at Point-blank range before being overrun. Later in the day the 11th R.B., accompanied by some of the artillerymen retook the position and were able to remove the breeches of the guns, before pulling back.