On 28th April four mines were exploded in front of the 6th Seaforth Highlanders and 8th Argyll and Sutherland Highlanders. The resultant casualties to these two battalions were 6 officers wounded at duty, 12 other ranks killed, 75 wounded, and 30 missing, believed buried. The explosions of these mines were followed by a forty-five minutes' intense bombardment. The Divisional artillery, however, opened a barrage on the enemy's lines opposite the newly-formed craters with such rapidity that he was unable to employ his infantry. Throughout the whole period the manner in which the artillery supported the infantry in this form of warfare was admirable, and gave the latter great encouragement. The explosion of mines became of such frequent occurrence that the troops became very expert in rapidly seizing and consolidating craters. Dumps were made at frequent intervals along the front containing all the materials required for consolidation. In a short time the troops could be relied on to establish themselves on the near lip, however unexpectedly a crater might be blown. This was largely due to the gallantry and initiative of the junior officers, on whose skill and leading success in these enterprises was dependent. Demonstrations were given in consolidation, and a platoon for each front-line battalion was ear-marked for the consolidation of any mine crater which might be blown on the battalion's front. A natural concomitant to mining was sniping. The lip of a crater affords an excellent post from which to snipe, particularly when, as was the case in this sector, the ground sloped from the German position towards the British. The trenches on this sector were also particularly open. After the enemy positions in this sector had been captured by the Division in April 1917, an examination was made of the German crater posts. It was astonishing to see to what an extent he could look down into the British trenches. It was realised at the time that men walking along the trenches were often under observation, and, indeed, the casualties from sniping proved that this was so. It was not, however, appreciated till later to what a degree men in the trenches, particularly the communication trenches, were visible to the Germans. In some places even the duck-boards at the bottom of the trenches were in enemy view. The result of this situation was that at first the enemy made a considerable bag by sniping; Colonel Campbell, commanding the 4th Seaforth Highlanders, was killed by a sniper the day after the Division had taken over the line. Within a fortnight his successor was killed in a similar way.