The defences of the enemy front line varied a little in degree, but hardly at all in kind, throughout the battlefield. The enemy wire was always deep, thick, and securely staked with iron supports, which were either crossed like the letter +X+, or upright, with loops to take the wire and shaped at one end like corkscrews so as to screw into the ground. The wire stood on these supports on a thick web, about four feet high and from thirty to forty feet across. The wire used was generally as thick as sailor's marline stuff, or two twisted rope-yarns. It contained, as a rule, some sixteen barbs to the foot. The wire used in front of our lines was generally galvanized, and remained grey after months of exposure. The enemy wire, not being galvanized, rusted to a black colour, and shows up black at a great distance. In places this web or barrier was supplemented with trip-wire, or wire placed just above the ground, so that the artillery observing officers might not see it and so not cause it to be destroyed. This trip-wire was as difficult to cross as the wire of the entanglements. In one place (near the Y Ravine at Beaumont Hamel) this trip-wire was used with thin iron spikes a yard long of the kind known as calthrops. The spikes were so placed in the ground that about one foot of spike projected. The scheme was that our men should catch their feet in the trip-wire, fall on the spikes, and be transfixed. In places, in front of the front line in the midst of his wire, sometimes even in front of the wire, the enemy had carefully hidden snipers and machine-gun posts. Sometimes these outside posts were connected with his front-line trench by tunnels, sometimes they were simply shell-holes, slightly altered with a spade to take the snipers and the gunners. These outside snipers had some success in the early parts of the battle. They caused losses among our men by firing in the midst of them and by shooting them in the backs after they had passed. Usually the posts were small oblong pans in the mud, in which the men lay. Sometimes they were deep narrow graves in which the men stood to fire through a funnel in the earth. Here and there, where the ground was favourable, especially when there was some little knop, hillock, or bulge of ground just outside their line, as near Gommecourt Park and close to the Sunken Road at Beaumont Hamel, he placed several such posts together. Outside Gommecourt, a slight lynchet near the enemy line was prepared for at least a dozen such posts invisible from any part of our line and not easily to be picked out by photograph, and so placed as to sweep at least a mile of No Man's Land. [Illustration: Sleighs used for conveying the Wounded through the Mud]