For seven days an artillery preparation of incredible intensity hammered the villages of Messines and Wytschaete, until they had completely disappeared. On June 7, about an hour before dawn, at 3.10 a.m., the sky was lit up by an intense light, while a series of terrific explosions were heard; nineteen mines, some of whose galleries had taken more than a year to bore, exploded along the enemy positions. The Germans were taken completely by surprise, and gave way before the impetuous onrush. In a few minutes their first line was carried along the whole of the attacked front. Then, almost without a pause, the British troops attacked the western slopes of the Messines-Wytschaete Ridge, and by about 6.30 a.m. held the crests along the whole line. The village of Messines offered resistance, but was captured by the New Zealanders in a vigorous attack, as was also the village of Wytschaete. By noon the second stage of the offensive was about to begin. Descending the eastern slopes of the ridge the British carried a second strong position, then attacked a fresh line--chiefly in Rayon Wood--in which were large shelters of reinforced concrete, each capable of holding a company. At about 4 p.m. Oosttaverne Village, lying west of the centre of the position, fell. At sun-down the day's objectives had been completely attained, and the advance at certain points exceeded two miles in depth. This fine success was due to the carefully detailed preparation carried out under the orders of General Herbert Plumer, to the destructive effect of the mines, to the violence and precision of the bombardment, to the excellent co-operation of the Air Forces, and to the harmonious working together of all arms. The tanks rendered excellent service. [Illustration: THE BRITISH OFFENSIVE OF JUNE 7, 1917, AGAINST MESSINES RIDGE, PRECEDED BY THE FIRING OF NINETEEN ENORMOUS MINES] The Germans made an effort to rally, but their first counter-attacks, near Oosttaverne and to the east of Messines, failed. At about 7 p.m., on June 8, a fresh German counter-attack was launched along the whole of the new front between St. Yvon and the Ypres-Comines Canal. Other engagements were fought to the east of Messines and near Klein Zillebeke. Although reinforced by fresh divisions, the German attack was broken by midnight. Resuming their offensive, the British, on the morning of June 11, captured the whole system of German trenches, nearly a mile in length, situated near Poterie Farm, to the south-east of Messines. The next day fresh progress was made along nearly two miles of the front to the north-east of Messines, and the hamlet of Gapaard occupied. [Illustration: THE FRONT LINE BEFORE THE ALLIES' OFFENSIVE OF JULY 31, 1917] After the offensive--limited in scope--of June 7, which reduced the salient, south of Ypres, the British continued to press the enemy. Frequent raids kept the Germans on the alert and secured important _points d'appui_.