THE BATTLE OF MESSINES The preliminary move is known as the Battle of Messines, and its purpose was to gain the high ground about Messines and Wytschaete as a flank bastion for the subsequent advance from Ypres. For while in German possession it gave the enemy com plete observation of the British trenches and forward battery positions, enabled them to command the British communications up to the Ypres salient, and to take in enfilade, or even in reverse, the trench positions therein. General Plumer and his II. Army, who had been acting as wardens of the Ypres front for two years, had been selected to carry out this operation, while the V. Army under General Gough had been transferred from the Somme to hold the line north of the II. Army. Preparations for the under taking had begun nearly a year before although their real develop ment dated from the winter. Thus when Haig asked Plumer, on May 7, when he would be ready to deliver the attack Plumer was able to say, "a month from to-day," and to keep his promise.
Messines was to be a strict siege operation, the capture of a fortified salient at the minimum cost of lives by the maximum substitution of mind (care in preparation) and material for man power. Mines, artillery, gas and tanks all contributed. But a contrary wind curtailed most of the scheme of gas projection, and the effect of the mines and artillery was so overwhelming that the tanks were hardly needed. On the centre corps front alone, of about three miles, a total of 718 guns and howitzers, 192 trench mortars, and 198 machine-guns was concentrated.
For the defence of this salient the Germans depended on two separate trench systems coinciding in trace with its arc, the more advanced one pushed down the forward slope of the high ground while the rear one followed its crest; they had also constructed two chord positions, stretching along the base of the salient on the reverse slope. The troops of the II. Army detailed for the enterprise were, from right to left, the II. Anzac Corps, with
the Australian 4th Division in support, the IX. Corps with the 11th Division in support, and the X. Corps with the 24th Division in support. There were thus nine divisions in front line and three in support. The fact that the attack would converge against a salient increased its chances, but it complicated the staff, troop, and artillery organization of the attack. For the sectors of each attacking corps were of varying depths, and contracted more and more in width up to the final objective which was the chord of the arc forming the salient. As, however, it was a siege opera tion, without any attempt at exploitation or a break-through, it was easier to avoid the congestion which had occurred at Arras (q.v.). The problem was further simplified by the plan of allotting sectors so that five of the divisions had sectors of equal breadth from front to rear, while the four which filled the interstices had smaller tasks. Further, when the main ridge was captured, fresh troops were to "leap-frog" through to gain the final Oosttaverne line across the base of the salient. The first bombardment and "wire-cutting" began on May 21, were devel oped on May 28 and culminated in a seven days' intense bom bardment, mingled with practice barrages to test the arrangements. The loss of surprise did not matter at Messines as it was a purely "limited" attack.
At 3.10 A.M. on June 7 the nineteen mines—one only had previ ously been blown by the enemy—were exploded, wrecking large portions of the Germans' front trenches. Simultaneously the barrage fell. When the debris and shock of the mines subsided, the infantry advanced and within a few minutes the whole of the enemy's front line system was overrun, almost without opposi tion. Resistance stiffened as the penetration was deepened, but the training of the infantry and the efficiency of the barrage enabled continuous progress to be made, and within three hours the whole crest of the ridge was secured.