Eight Tanks were to operate against Vimy Heights and the village and heights of Thélus, considered amongst the most formidable enemy positions in France. Tanks were to play a subsidiary part, as the soil here was a soft heavy loam, highly unfavourable to Tanks. 2. _With the Third Army_ (“C” Battalion): Forty Tanks were to operate, some north, some south of the river Scarpe. This sector contained several notorious strong points, such as the Harp and Telegraph Hill. The ground here was hard and chalky and afforded good going for Tanks, though it was intersected by old trench lines and had been heavily crumped. 3. _With the Fifth Army_ (“D” Battalion): Twelve Tanks were to operate in the region of Lagnicourt. Here the ground conditions were bad. The roads especially had been destroyed, and it was found impossible to bring up sufficient artillery for a preliminary bombardment. Therefore, on this sector Tanks were to play a leading part, preceding the infantry and largely replacing the barrage. This action was not to be launched till about forty-eight hours after that on the other two sectors. Zero day was to be April 9, and the attack was to be made at dawn. III Till the night before the battle the work of preparation had gone smoothly. Maps had been issued, stores stood ready, pack animals and limbers were at hand to form advanced dumps. The Reconnaissance Officers had taken little parties of Tank Commanders to the best observation posts in their sectors, and had there shown them the ground they must cross and expounded their maps to them. All the Tanks had been brought safely to their railheads and successfully detrained, and now they lay waiting in their tankodromes. “C” (afterwards No. 3) Battalion lay in Arras itself. The town had been most carefully prepared for troops to assemble and wait in. Great chalk quarries underlay it, and these had been linked up and lit with electricity, and here two divisions could lie thirty feet underground secure from the heaviest shelling. The Tanks had chosen the Citadel as their assembly place. There in the great grassy ditch of the old Vauban Fort they lay, nosing for cover into the re-entrant angles of the tall cliff of mellow brickwork that towered above them. As soon as it was dark, on the night of April 8–9, the Tanks set off on their journey up the line. There had been a question as to the route which these Tanks were to follow. The alternatives were a long detour round the head of a shallow valley or a short cut over ground of questionable soundness. The short cut had finally been decided upon, and, on the Reconnaissance Officer’s report, the Battalion had applied for enough brushwood and sleepers to build a rough causeway.