Preparatory to the attack, some twenty great mines had been driven into the long, low hill, which is really little more than a slope, attaining a height of 250 feet at the summit. These mines contained 600 tons of explosives, and had been the work of constant relays of miners during many months. These tunnelling companies of miners, drawn from all sorts of material and officered by mining engineers and foremen, did some splendid work in the war, and the British finally outfought the Germans under the earth as completely as they did both on it and above it. The accumulation of guns was even greater than at Arras, and they were packed into about half the length of front, so that the effect of the massed fire when it broke out in the morning of June 7 was crushing to an extent never before known in warfare. What with the explosions of the mines and the downpour of shells, the German front line, with its garrison, may be said to have utterly disappeared, so that when at 3.20 in the first faint flush of a summer morning the infantry dashed forward to the attack, the path of victory had already been laid out before them. Let us examine the general composition of the British line before we follow the fortunes of the various units. General Plumer's Army had been moved down the line so as to cover all its objectives, and Gough's Fifth Army from the south had been put in to the north of it, occupying the actual salient. This Army was not in the first instance engaged. The Second Army consisted of three Corps. The northern of these was Morland's Tenth Corps, which was in the {97} region of St. Eloi. This Corps consisted, counting from the north, of the Twenty-third, Forty-seventh and Forty-first Divisions with the Twenty-fourth in reserve. Upon its right, facing Wytschaete, was Hamilton Gordon's Ninth Corps, containing from the north the Nineteenth, Sixteenth, and Thirty-sixth Divisions, with the Eleventh in reserve. Still farther to the right was the Second Anzac Corps (Godley) facing Messines with the Twenty-fifth British Division, the New Zealanders, and the Third Australians in line from the north, and the Fourth Australians in reserve. This was the British battle-line upon the eventful dawn of June 7, 1917.