At 5.50 A.M. the gas should have commenced, but at that hour it was practically calm, and what wind there was made it unsafe to let it off in certain bays. In these bays the men of the detachments, on their own initiative, did not turn it on. Soon after the first cocks were turned on, a gust of wind from the south-east turned the gas into our own trenches. All gas was immediately turned off, the detachments doing this on their own initiative, but considerable quantities entered our own trenches and caused many casualties in the 2nd Black Watch on the leeward of our front. The intensive bombardment commenced at 5.50 A.M. and was satisfactory, the field guns and the Hotchkiss gun in the front parapet participating. The Infantry began to cross the parapet just before the assault, under cover of the smoke and of the Artillery bombardment, the Artillery lifting 100 yards and increasing their rate of fire, so as to conceal the increase of range and prevent the enemy realising that the assault was about to commence. This, combined with the smoke, had the desired effect, as the enemy was not expecting the assault at the moment it was delivered, and there was practically no hostile fire while the assaulting troops crossed the ground between the two front lines. At 6 A.M. the assault commenced. Dense clouds of smoke, the result of the barrage on the right or south flank, travelling in a north-easterly direction made observation difficult, and caused some confusion and mistakes in direction. The Garhwal Brigade got up to the German wire, which was found to be impassable opposite the 3rd Gurkha Rifles and the right of the Leicesters. There the lanes cut by our Artillery had been filled up during the night with rolls of French wire. This stopped the assault sufficiently to give the enemy time to man his parapets and prevent these troops making good the attack. The left of the Leicesters and the 2/8th Gurkhas, however, found the wire destroyed and penetrated into the enemy’s line. In front of the Bareilly Brigade the wire had been destroyed by our Artillery and all three battalions got into the enemy’s trenches with slight opposition. On the left, the Black Watch had to go through our own gas, which the wind had not been strong enough to disperse, and suffered more casualties. This battalion was not free from the vapour until it got into the enemy’s lines. The smoke clouds, which the calmness and dampness of the day had turned into thick fog, prevented observation and hid guiding landmarks, and considerable intermingling of units occurred after the assault. Communication also was difficult, as the lines laid in advance of our front parapet by the assaulting Infantry and the R.A. officers accompanying them were continually being cut. This was especially the case with the Infantry communications, and the earliest information was obtained from Artillery Observation officers, which proved generally reliable.