2. That the fullest use must at all times be made of mechanical weapons--_i.e._, guns, machine-guns, trench-mortars, &c. The minimum use of infantry; to rely for success on the weight of infantry, either in attack or defence, was to ensure unnecessary casualties. 3. That troops must always be in depth; they must neither attack nor defend in one or two dense lines of men, but in a succession of well-extended lines. He also made a point of impressing on all that a leader without personality will achieve nothing. Though the application of these theories may not at this time have reached its full development, the problems connected with them had certainly been considerably discussed before the battle of Arras took place. The 152nd and 154th Brigades were detailed for the original attack, it being the custom of the Division for the brigades to take part in the initial operations of a new battle in turn. The German trenches on the battle fronts of the two brigades were therefore taped out exactly according to scale in the vicinity of the billeting areas. The men were then continually practised in the attack over the taped-out course. The 18-pounder barrage was represented by men with signalling flags and by the pipers, under the command of an artillery officer. Hostile machine-guns were indicated by the drummers. The attack was practised so often that the men obtained a thorough knowledge of the distances from one objective to the next, of the length of the pauses in the barrage, and the trace of the enemy's trenches. Various raids which were carried out preparatory to this attack had brought out some valuable lessons concerning the close combat. In these raids it had become clear that the blind leap into a trench was not a sound policy. Not only were the German trenches in many places of a great depth, but they also contained many straight lengths of trench covered by a machine-gun mounted on the top step or a dug-out cut in the side of a traverse. These machine-guns were sited so as to fire straight along the trench as soon as any attacking party had leapt into it. Considerable pains were therefore taken to train the men not to rush blindly at their objective, but to come up on to the parapet properly extended ("carrying a good head," as the General put it), and shoot down all the garrison of the trench that were visible before they entered it. The men were therefore constantly practised in assaulting reserve trenches near Villers Chatel, in which targets were placed representing the trench garrisons. On reaching this trench each man fired five live rounds at the targets. A good many rounds ricochetted into the adjacent parts of France, but fortunately no damage appears to have been done to the local inhabitants. On the other hand, the men rapidly began to acquire the right instincts for engaging the Germans in close combat.