During the afternoon and evening of 1st August the 154th Brigade, which had as yet not been employed in the operations at all, relieved the 152nd and 153rd Brigades, and remained in the line until 8th August, when the whole Division was relieved. CHAPTER XII. POELCAPPELLE. From the 8th August until 29th the Division remained at rest in the St Janster Biezen area, with the exception of the 154th Infantry Brigade, which moved back to the Eperleques area. Training was carried out as usual, particular attention again being given to the practising of platoons in attacking under cover of their own fire. On 17th August Brigadier-General A. T. Beckwith, C.M.G., D.S.O., Hampshire Regiment, took over command of the 153rd Brigade, having already had a distinguished career as a battalion commander in the 29th Division. He had left one Division with a distinct identity of its own to join another with an equally distinct identity. His great capacity for detail being admirably adapted to the system on which the 51st worked both in attack and defence, enabled him quickly to become one of its main supports. On 20th August the G.O.C. 51st Division assumed command of the left sector of the XVIIIth Corps front, the 152nd Brigade having taken over the line. The trench area was situated some half a mile away from the remains of the village of Langemarck and just east of the Langemarck-Gheluvelt road, the Divisional frontage being about 1500 yards in breadth. The Division continued holding this line until 20th September, when an attack was launched. This period was remarkable on account of three things. First, the mud, which reproduced conditions similar to, if not worse than, those at Courcelette. The ground throughout the whole front was so sodden with rain and churned up by shell-fire as to be impassable to troops in any numbers. The second feature was a consistently lavish use of the recently-introduced mustard gas, which caused numerous cases of slightly-gassed men, and a lesser number of men seriously gassed. The latter suffered indescribable agonies, and either ultimately died, or made an insufficient recovery ever to return to the ranks as whole men. The mustard gas shell proved itself to be a weapon that was liable to cause serious losses unless all measures for anti-gas defence were maintained at a high level of efficiency. It was, however, a persistent gas, and might cause casualties hours and even days after it had been used, so that the enemy could never employ it on an area which he intended to attack in the immediate future.