Field guns laid down a barrage that mostly advanced at a rate of in three minutes while medium and heavy howitzers established a series of standing barrages further ahead against known defensive systems. During the early fighting, the German divisional artilleries, despite many losses, were able to maintain their defensive firing. As the Canadian assault advanced, it overran many of the German guns because large numbers of their draught horses had been killed in the initial gas attack. The 1st, 2nd and 3rd Canadian Divisions reported reaching and capturing their first objective, the Black Line, by 6:25 am. The 4th Canadian Division encountered a great deal of trouble during its advance and was unable to complete its first objective until some hours later. After a planned pause when the 1st, 2nd and 3rd Canadian Divisions consolidated their positions, the advance resumed. Shortly after 7:00 am, the 1st Canadian Division captured the left half of its second objective, the Red Line and moved the 1st Canadian Brigade forward to mount an attack on the remainder. The 2nd Canadian Division reported reaching the Red Line and capturing the village of Les Tilleuls at approximately the same time.