The introduction of this system necessitated the laying out of a complete new system of defence, which, though existing trenches were largely utilised, entailed a vast amount of new work in the sector. In carrying out this work much difficulty was at first encountered owing to the inexperience of the troops, and the fact that the bulk of them were not fully developed men. The Jocks, however, played up magnificently, almost surpassing their efforts in the early part of the year; and in a few weeks the defences, though not actually completed, contained the framework of a series of well-wired localities, in which the troops could have offered a stubborn resistance. It was, in fact, evident from the manner in which the work was carried out that, in spite of the immense number of casualties sustained in the last two months, the traditions established in the Division for hard work were being well maintained by the new drafts. On one occasion while this work was in progress, a party was working at night in front of Bailleul when a machine-gun opened, and a boy slid from the berm into the trench and lay on the duck-board groaning heavily. The platoon sergeant jumped down beside him and said, "What are ye groaning for, laddie?" "I've a bullet in the fleshy part of my leg," was the reply. "Fleshy part of the leg!" said the war-weary sergeant, with visions of a peaceful spell at home, "what the h----l are you complaining about?" Throughout this period there were occasions on which the enemy's artillery was extremely active. High-velocity guns paid considerable attention to the back areas, particularly to Ecurie, Ecoivres, and Marœuil. On one occasion a shell from one of them landed in the machine-gun battalion camp at Ecurie, killing two men and wounding Major Clarke and Captain Biddulph, the second in command and adjutant respectively, and wounding seven other ranks. The battery positions of the heavy artillery and the Concrete Road, a famous overland route made of concrete running from Roclincourt to the Arras-Lens Railway, received a daily ration of heavy shells. The enemy also occasionally carried out intense bombardments with gas shells. On one particular occasion, the night 16-17th May, he fired three half-hour violent bursts of mustard-gas shell at intervals of three hours, causing casualties to 3 officers and 139 other ranks of the 7th Argyll and Sutherland Highlanders. On 25th May over 800 shells were fired into the area near Thelus by 4·2, 5·9, and 8-inch howitzers without a single casualty being caused. Shellings of this nature continued until 9th June, gas shells frequently being mixed with high explosive; but the dug-out system had been so rapidly improved under the directing energy of Colonel Fleming, the C.R.E., that only slight casualties were caused.