At 1 A.M. the leading company started for the assembly positions, and although the guide twice lost his way it arrived at the destination at 3 A.M. An hour later Lord Lascelles went round the positions and could find no trace of the other three companies. At 5.5 A.M., the hour at which the Battalion was to advance, they arrived, having been on the march for four hours, owing to inefficient guides.
The Germans had meanwhile decided not to wait for the attack and had already retired when the Battalion commenced to advance, so that there was no fighting. When No. 1 and No. 2 Companies, under Captain Fryer and Captain Dury, reached the final objective, it was merely a matter of rounding up a certain number of deserters. Lord Lascelles, on going up to the leading companies, found a stretch of undulating country in front with no sign of the enemy, and ordered an advance to the next ridge, at the same time directing No. 3 Company, under Lieutenant Cornish in support, and No. 4 Company, under Captain Hirst in reserve, to move forward as far as the position already occupied by the leading companies. This sweeping advance with no apparent opposition somewhat confused the leading companies, which were accustomed during the long period of trench warfare to short advances with definite objectives.
The fatigue of the men was beginning to tell, and this last advance was a distinct effort, but by two o'clock in the afternoon the leading companies had consolidated the position in Boursies. There were no casualties, although the enemy put up a few shells over the Battalion, as it topped the ridge 500 yards west of the village. During the afternoon the German artillery became very busy, and interfered a good deal with the patrols, but otherwise caused little or no damage. The men had been on the move since dawn the day before, and were consequently exhausted, but the Germans made no attempt to counter-attack, and it was therefore possible to get some rest.
At 5 o'clock the following morning the 3rd Guards Brigade passed through the Battalion, which was withdrawn to watch the exposed right flank. The visibility was good, and a few sentries were all that were required, while the remainder of the Battalion obtained some rest. On the 5th the Battalion relieved the Welsh Guards in the front line, and Lord Lascelles decided to move the Battalion Headquarters farther forward, and to hand over what had been the Welsh Guards Headquarters to the Medical Officer for an aid-post. Nos. 3 and 4 Companies were placed in the front line, with Nos. 1 and 2 in support. The right of the Battalion was not in touch with any troops, there being a gap of some 500 yards, and this was accounted for by the fact that the ground was covered with wire of the old Hindenburg line and of the old British line facing it. This wire was almost impenetrable laterally, and was at right angles to the line held by the Battalion. The enemy was in considerable strength in front, and held some 400 yards west of the Canal du Nord as an outpost line in the old maze of trenches, with a strong defensive position behind the Canal. The ground sloped down to the Canal, and the farther the Battalion advanced, the more they were overlooked from the opposite slope; but the necessity of gaining touch with the 1st Battalion King's Royal Rifles made an advance necessary. The line of resistance, about 600 yards behind the front line, which the Battalion received instructions to dig, was nearly finished, when the enemy put a concentrated gas bombardment on the valley, where the Company Headquarters of the two companies in support were placed. For an hour the Germans bombarded the valley with sneezing-gas shells, and all the officers and men kept on their masks, but when the gas bombardment appeared to cease and was succeeded by one of H.E. shells, every one incautiously took off his mask. This new bombardment proved to be one of mustard gas. By the time this was realised every one was being sick, and all the officers and N.C.O.'s were casualties. Lord Lascelles came up from Battalion Headquarters to see what had happened, and met Captain Dury being led away blind. There were 61 men in No. 1 Company and 30 men in No. 2 who had been gassed, in addition to the following officers: Second Lieutenant S. Calvocoressi, Captain G. Dury, Second Lieutenant W. B. L. Manley, Lieutenant H. P. Gordon, and Second Lieutenant R. K. Henderson.
In the meantime Lieutenant Cornish, commanding No. 3 Company, had received orders from Lord Lascelles to close the gap on his right, and after reconnoitring the situation had established a liaison post with the King's Royal Rifles at Joan Post. When darkness came he managed to send out more men, and added two fresh posts south of Goat Trench; but the ground to be covered was over 500 yards, and the difficulty was that the line from the right of the Battalion to the left of the King's Royal Rifles ran diagonally over a crest, and not parallel to it. Lines of very thick and strong wire ran in irregular lines, and in various directions. What therefore seemed fairly simple by daylight was extremely difficult in the dark, since no patrol could keep direction on account of the wire. A compass was useless, owing to the wire, and there were no landmarks. Lord Lascelles, who was not at all happy about his right flank, ordered Lieutenant Cornish to double his liaison post, and to put up a Véry light perpendicular at dusk from his post on the left of the gap, so that a detachment from the liaison post could work towards it.
These measures, although far from satisfactory, were the best that could be done in the circumstances, and Lieutenant Cornish was afterwards highly commended for the energy and resource which he showed in dealing with an admittedly difficult situation.
On the 8th the Battalion was relieved by the 2nd Battalion Grenadiers, and retired to some trenches in Dunhelm Avenue. From the 8th to the 15th the whole of the 2nd Brigade went into reserve positions near Lagnicourt, where no incidents of any importance occurred. As a draft was shortly expected, the companies were not equalised in strength, but it was Nos. 1 and 2 Companies that had suffered most, and, as the other two companies would have to lead the attack at the end of the month, there was no objection to the half-assimilated draft being in reserve.
On the 20th the Battalion was warned that it would shortly have to take part in the attack on the Canal du Nord, and that it would relieve the 1st Battalion Scots Guards on the night of the 21st. A piece of ground was at once selected for practice purposes, and the enemy's trenches and salient features were taped out on it, while the Royal Engineers constructed a model of the area to be attacked. The expected draft arrived just in time to take part in the rehearsal, and was absorbed in Nos. 1 and 2 Companies. The following day after a Company Commanders' conference, the details of the attack were carefully explained by the Commanding Officer, Lord Lascelles, who had attended a conference at Brigade Headquarters. No. 3 Company and one platoon of No. 4 were to attack Slag Heap; the remainder of No. 4 Company would be in support; No. 2 Company would remain where it was in the front line, and No. 1 would be in Brigade Reserve. Thus all four companies were to be more or less in the front line, but No. 4 Company, under Lieutenant Bunbury, was the one most likely to come into touch with the enemy. During the relief No. 4 Company was raided, but the Welsh Guards had not yet left the line, and the enemy consequently received a very warm reception. The possibility of an attack on that part of the line had already occurred to Lieutenant Bunbury, as a similar raid had been attempted two days before, and the ground being a regular rabbit-warren of disused trenches made it extremely difficult to guard against a surprise; but he kept his company constantly on the alert, and was ready for the Germans when they came.
On the 25th a heavy barrage descended on the whole front line, and all wires became disconnected. The enemy raided the position of the line occupied by No. 4 Company, and managed to get into trenches at an unoccupied spot, but were ejected by a patrol. There were a few casualties from the barrage, but no men missing. On the following day detailed orders for the attack were issued, and the Battalion proceeded to the assembly position.