On 21st May the enemy became extremely active. The Divisional artillery were heavily bombarded during the afternoon and evening with lachrymatory shells, as also were the communication trenches. At the same time the trenches of the 25th Division on the left of the Highland Division, and of the 47th Division, were intensely bombarded. Marœuil, Anzin, and Mont St Eloi were also shelled during the night, as well as several villages in rear of the 25th and 47th Divisional areas. At Marœuil an 8-inch shell burst in the 152nd Brigade headquarter office within a few seconds of the clerks having left it for the cellar, completely wrecking it, and killing the staff captain's two horses, which were tethered outside it. This bombardment culminated in a successful hostile attack, the enemy, with apparently little difficulty, attaining his object and establishing himself firmly on the western slopes of the Vimy Ridge. The cause of his success was due to the fact that he succeeded in secretly concentrating a large force of artillery with which to support his attack. He then subjected all the trenches involved to a bombardment of an intensity which in those days was considered unparalleled. The garrisons of the trenches attacked were almost completely without the protection of shell-proof dug-outs, and the defenders were thus for the most part killed or wounded by the bombardment before the infantry attack was launched. At this juncture the Divisional sector was considerably increased; in fact, the Division took over the whole front of the XVIIth Corps. This extension was caused by the necessity of withdrawing troops from this part of the line preparatory to the Somme battle. The 152nd Brigade was withdrawn on 23rd May, the 153rd and 154th Brigades extending their brigade sectors so as to include the area previously held by the 152nd. On the nights 1-2nd June and 2-3rd the 152nd Brigade moved northwards and relieved troops of the 25th Division in the Neuville St Vaast sector. To conceal from the enemy the fact that the whole Corps front was held by the Highland Division alone, the kilt was no longer worn by the troops in the line, khaki trousers being issued instead. The situation in the new sector taken over by the 152nd Brigade was a curious one. The extreme left of the enemy's attack on the Vimy Ridge rested on the left boundary of the new sector. Thus on the brigade left boundary in the front and support lines the British and the Germans occupied the same trenches, sandbag bombing-stops alone separating them. In some cases the British held communication trenches while the Germans occupied the trench into which the communication trench led, bombing-blocks again separating the two forces.