Thus the newly formed 4th Guards Brigade joined the Thirty-First Division. On the 14th Major-General Sir Charles Fergusson, Commanding the Thirteenth Corps, inspected the Battalion, and expressed himself very pleased with its appearance on parade. On the 17th the Battalion relieved the Durham Light Infantry in the line near Arleux Loop, and was subjected to a slight shelling. This was the new Brigade's first tour in the trenches, and the 4th Battalion was the first of the three Battalions to go into the front line. The line taken over was an example of the new system of holding the front in depth. The Brigade frontage, 2000 yards in length, was held by one Battalion, and constituted the outpost line. Held very lightly by posts at long intervals, it was supported some 1000 yards in rear by a trench, known as the Arleux Loop, South and North, where the Battalion Headquarters were situated together with one company in reserve. Lieut.-Colonel Pilcher was aware that the arrival of a fresh Battalion in the line was likely to be observed by the enemy, and that therefore a raid was highly probable. If any confirmation of this theory was required it had already been supplied by a prisoner, who had been captured before the relief, and had stated that the enemy suspected the presence of the Guards Division, and intended shortly to make a raid to confirm the fact. Nothing, however, was observed either to indicate the exact time or the locality; in fact, everything seemed normal, and the officer commanding the 2nd Battalion Irish Guards went round the posts with Lieut.-Colonel Pilcher in the usual way in order to make the necessary arrangements for the relief the next morning. From the evidence of the single surviving prisoner, who was captured, it was clear that the Germans had planned and rehearsed every detail of the coming raid with great thoroughness. Practice trenches, made from aeroplane photographs, had been dug in Beaumont, and the raiders were minutely trained in their duties. All the men who were to take part in the raid had been withdrawn from the line for three weeks, and had been well fed and cared for. They were the pick of the 469th German Infantry Regiment, and had been selected on account of their physique and proved courage. Their equipment was of high quality, with every detail carefully thought out; it consisted of a short, light rifle of 1917 pattern with a leather sling, a trench dagger, an automatic pistol, wire-cutters, a watch, and a canvas bag for carrying stick-bombs.