This operation roused the enemy considerably, and he shelled the forward area throughout the night. In this bombardment he used a considerable number of shells containing phosgene gas. This was one of the earliest occasions on which this form of gas was used. It was particularly insidious, as at first it did not cause any inconvenience, and its smell was not offensive, being similar to that of sweet apples. Meanwhile the brigade in support had been kept fully occupied. The intense heat created a great demand for water for the first-line troops. The water supply in the forward area was, however, non-existent, so that a dump of petrol tins of water had to be formed in the Happy Valley. From this dump all the water used in the forward area was carried by the supporting brigade. Similarly, with no light railways in repair, every round of S.A.A. bombs, trench-mortar ammunition, Very lights, barbed wire, screw pickets, &c., had to be carried forward by man power. The result was that practically every man in the supporting brigade made at least one journey daily from the dumps at the south-east corner of Mametz Wood to the forward dumps in rear of High Wood. The labour thus entailed, coupled with the fact that the supporting brigade lived in a heavily-shelled area with insufficient dug-out accommodation, meant that the troops had lost much of their fighting efficiency before they went into the line. In the circumstances there was, however, no alternative. On the 26th July the 153rd Brigade relieved the 154th Brigade, and the 152nd Brigade moved forward to the support position. This relief was considerably interrupted by a further lavish use of phosgene by the Germans. The work of consolidating and digging more trenches south and south-west of the wood was continued, as until touch in the front line could be obtained on the left, that flank was in the air. On the 27th the forward area and the supporting brigade (152nd) in Mametz Valley were heavily shelled all night. This shelling was intense, it being estimated that two shells per minute burst in the area close to brigade headquarters alone throughout the night; 77 mm. gas shells were primarily used, but 5·9's were also from time to time employed freely. As a result of this bombardment the 8th Argyll and Sutherland Highlanders alone sustained eighty gas casualties. During the following day the 153rd Brigade co-operated in an attack on Longueval by rifle and machine-gun and Stokes mortar fire. They, however, took no part in the infantry action. During the night 27-28th July, connection in the front line was established about 200 yards north-east of the Bazentin Windmill by the 6th Black Watch with the 29th Division. For the first time in this sector a continuous line of defence was presented to the enemy.