Ludendorff’s plan was based upon the highly specialized training of certain units, and was a legitimate conclusion from the German use of “storm troops.” The first point was the absence of any preliminary massing near the front of attack. Men were brought up by night marches just before zero hour, and secrecy was thus obtained for the assembly. Again, there was no long bombardment to alarm the enemy, and the guns began at the moment when the infantry advanced, the enemy’s back areas being confused by a deluge of gas shells. The assault was made by picked troops in open order, or rather in small clusters, carrying light trench mortars and many machine guns, with the field batteries close behind them in support. The actual mode of attack, which the French called “infiltration,” may be likened to a hand, of which the finger-tips are shod with steel, and which is pushed into a soft substance. The picked troops at the finger-ends made gaps through which others poured, till each section of the defence found itself outflanked and encircled. A system of flares and rockets enabled the following troops to learn where the picked troops had made the breach, and the artillery came close behind the infantry. The men had unlimited objectives, and carried iron rations for several days. When one division had reached the end of its strength, another took its place, so that the advance resembled a continuous game of leap-frog. This method was the opposite of the old German mass attack, which had seen a succession of hammer-blows on one section of front. It was strictly the filtering of a great army into a hostile position, so that each part was turned, and the whole front was first dislocated and then crumbled. This might be achieved by inferior numbers; but a local numerical superiority was aimed at to ensure a complete victory by pushing far behind into unprotected areas. Advance was to be measured not by metres but by miles, and in any case was to proceed far enough to capture the enemy’s artillery positions. Obviously the effect would be cumulative, the momentum of the attack would grow, and, if it was not stopped in the battle-zone, it would be far harder to stop in the hinterland. It was no case of an isolated stroke, but of a creeping sickness, which might demoralize a hundred miles of front. Ludendorff was confident, for he saw his way presently to a numerical superiority in the West, and he had devised tactics which must come with deadly effect upon an enemy prepared to meet only the old methods. But his plan demanded immediate success. A protracted battle would destroy the picked troops, and without them the new tactics were futile.