On the first day of June, 1916, the front of the 36th Division was held by the 107th Brigade, the 108th being in support in the neighbourhood of Martinsart, and the 109th training. To permit the two latter Brigades to train together, the 147th Brigade of the 49th Division was ordered to relieve the 108th and take over its working parties. The 108th Brigade then moved back to Varennes, and the neighbouring villages of Harponville and Léalvillers. Training was carried out over an elaborate system of dummy trenches marked out with plough and spade, near Clairfaye Farm, to represent those of the German system to be attacked. It was largely due to this preparation that the men knew their task so well, and were able to push on to their objectives when their leaders had fallen. On the 5th a raid was carried out by a party of the 12th Rifles, sent up from the training area, on the German sap that ran parallel with the main railway line north of the Ancre.[19] The wire was cut by an ammonal torpedo. This was a zinc tube, three inches in diameter, filled with ammonal. Each tube was about six feet in length, but tubes could be connected up with bayonet joints, and any length of torpedo thus made. It was generally fired by a sapper accompanying the raiding party. The Germans had run back or taken to their dug-outs under the fire of our artillery, and few were seen. The dug-outs were bombed, and an officer shot. Two tunnels leading toward the British lines were discovered, one containing fourteen high-tension copper wires, which seemed to point to mining with a mechanical digger. The heads of these saps were blown in by the engineers who accompanied the raiding party. Five nights later the Germans retaliated upon the little salient in the British line opposite, known as the William Redan, then held by the 15th Rifles. After our trenches had been pounded by a bombardment of half an hour, the raiders advanced. They suffered loss from our barrage, and not more than half a dozen ever actually entered our trench. Half a minute's bitter hand-to-hand fighting, and they were out of it again, bearing with them the leader of the raid, who had been shot by a British officer. Our trenches were considerably damaged, but casualties were not heavy.