But it was the machine-guns in the "pill-boxes," and the excellent fashion in which they were defended, that were by far the most fatal obstacles. The new German methods of defence in depth depended, in Flanders, upon the concrete structures built in and around the foundations of the destroyed farms with which that countryside is studded. They served their purpose admirably. Few that were captured by us were found to have been damaged by artillery. The British heavy artillery was firing from a salient, instead of, as at Messines, upon a salient. It had against it a far greater weight of German metal than in that battle, and suffered far more heavily from counter-battery. The German artillery dominated ours in the early stages of the battle, certainly in position, probably also in actual gun-power. The observation of the latter was almost worthless. And where any could be obtained it was well-nigh impossible to identify the "pill-boxes" from map to ground. An instance given by the G.O.C. 109th Brigade, General Ricardo, is illuminating. A few days prior to the attack he arranged with a liaison officer from the Corps Heavy Artillery a series of three-minute bombardments of certain strong points, with pauses between, so that it should be clear to the observers exactly which was being shelled, to correct the many various readings of maps and photographs. In several cases, he states, the concentration, nominally upon one strong point, covered many hundred yards. The same considerations applied to the cutting of wire, not nearly so effective as at Messines, through no fault of the gunners of the Division and of the batteries working beside them. The "pill-boxes," which were mainly responsible for the losses of the troops in the attack of July the 31st, were standing intact and garrisoned on the 16th of August. The claims of counter-battery sometimes prevented demands for re-bombardment being fully met.