The advance of the 5th Seaforth Highlanders and of the 8th Argyll and Sutherland Highlanders had been considerably interfered with in an unexpected manner. As the troops for the Blue line were crossing the Black line, an enormous explosion occurred. As a result a number of men were buried and several killed in both battalions. It was assumed that the Germans must have intentionally exploded a Minenwerfer bomb store, as shortly after the explosion six Germans voluntarily emerged from a dug-out. These men were assumed to have been responsible for this disaster, and were immediately killed. Eight hours and forty-eight minutes after the attack had been launched the 152nd Brigade had captured the whole of the Blue line, and were in touch in it with the 154th Brigade. On the 154th Brigade front, though the Blue line was captured throughout the front, the fighting had been severe. The 4th Gordon Highlanders had sustained such serious losses in their fight for the Swischen Stellung that, in consequence, their two remaining companies were sent forward to consolidate the Blue line. Meanwhile the Canadians on the left hand had been completely successful in their advance, and were pushing on exactly according to plan, while the 34th Division on the right was also reported to be holding the Blue line. The capture of this line had been most materially assisted by the initiative of Captain Saulez of "D" Battery, 64th Brigade R.F.A. He observed from his observation-post a German machine-gun in action at the junction of a communication trench and the Blue line, holding off the infantry advance. He therefore telephoned to his own battery, and turned a section of howitzers from firing on the barrage on to the machine-gun. By this means he put the gun out of action, and enabled the infantry to continue their advance. Captain Saulez' shooting was admirable, and his action undoubtedly saved the infantry from many casualties. Unfortunately, he was himself killed in the later stages of this battle, a shell bursting in a trench shelter in which he was lying. At 3.15 P.M. the enemy was turned out of a line known as Regiment Weg, which ran in rear of the Blue line opposite the 152nd Brigade front. Meanwhile the 154th Brigade had pushed on towards the Brown line, and were reported to have reached Tommy Trench at 1.40 P.M. After the capture of the Regiment Weg, the 152nd Brigade were unable to continue their advance, as they were held up by Germans holding Elect Trench, which was situated about half-way between the Blue and Brown lines. At 6.30 P.M. a message was received that the 154th Brigade had reached the Brown line, and were in touch with the Canadians at Commandant's House. At the same time the 34th Division reported that they were not in the Brown line. Orders were therefore issued for the 152nd Brigade and the 103rd Infantry Brigade of the 34th Division to assault the Brown line under cover of darkness.