The line held by the Brigade extended from Judas Farm near St Leger, where it was in close touch with the Division on the right, in front of Boyelles and Boiry-Becquerelle to the north branch of the Cojeul River. North of the river the line was continued by the 30th Division, who were endeavouring to force the villages of St Martin and Henin. The Battalion had pushed outposts beyond its main line on the railway to the Boiry-St Leger Road, but all attempts to continue the general advance beyond this line were frustrated by the heavy machine-gun and shell fire with which the enemy sprayed the forward slopes of the ridge down which the advance was to be made. At the same time signs were not wanting that his withdrawal had not reached its limit, for fires were observed in Henin and Croisilles which indicated that the systematic destruction which hitherto had been the prelude to his retirement was proceeding with unabated vigour. On the 21st the 2/4th Londons were relieved by the 2/3rd in the right subsector and withdrew to Boiry-St Martin in reserve. For three days the Battalion remained here under conditions of extreme discomfort. The weather was exceptionally severe and the ground was covered with snow, while the open and bare hillsides were swept by biting winds. Billets were non-existent owing to the total destruction of the village, so that the change from the front line to reserve brought very little of rest or easier conditions. Indeed throughout this period of the advance the terrible exposure proved a far more serious enemy than the Germans themselves, and the casualties caused through it were five times more numerous than those caused by wounds. The Hindenburg line was now within measurable distance, and the salient previously held by the enemy being almost entirely flattened out it was found possible to withdraw several divisions now in action. This was the more desirable not only for the provision of as many reserve divisions as possible for the impending offensive against the Vimy Ridge, but also for the tasks of rendering the devastated region covered by the advance habitable to our forces, of repairing the ruined roads, and of bringing forward the supplies of material necessary for further operations. One of the important gains of the advance was the reopening of direct lateral communication between Arras and Albert. With their usual thoroughness the Germans had completely destroyed the railway connecting these two towns, the track being torn up and the bridges demolished; and the complete reconstruction of it presented one of the most pressing necessities in the organisation of the new defences. The 58th Division, in accordance with this programme, was now withdrawn, and on the 25th March the 173rd Brigade handed over its sector to the 174th and withdrew to Pommier, the 2/4th Londons being billeted at Monchy and put to work on repairing the roads.