The opening of the main operation was no surprise to the enemy. Prisoners taken during the attack admitted that they had expected it and had been "standing-to" for a fortnight in anticipation; and orders which were captured confirmed this statement, for they contained elaborate instructions in the method of procedure to be adopted when the attack was launched. Two hours before the advance began that summer morning the Germans were sending streams of gas shells into the district around Maroc and the Lens-Béthune road, while a 5.9 howitzer was playing on Loos at intervals of five minutes. When our barrage opened the 7th Battalion went forward and formed up in No Man's Land in the rear of the 10th Battalion which was to capture the front German line. At first there was a slight mix-up of battalions owing to enemy fire, but before long, though only after heavy fighting, the objectives were gained with the exception of the centre where our men were held up by machine-gun fire from Cité St. Auguste and the brickworks. In time, however, reinforcements arrived and that obstacle was removed. For three days the fighting was the fiercest the Canadian battalions had up till then experienced. The Germans were in no mood to give up their positions without stubborn resistance and the struggle ebbed and flowed day and night with bitter violence. On the front on which the 2nd Division attacked many Germans held out in small parties hidden in ruined houses and in deep cellars until cleared out by bomb and bayonet, while counter-attack after counter-attack was thrown against the battalions which had succeeded in clearing the German trenches. With the 7th Battalion were sixteen stretcher-bearers, including O'Rourke. Out of that sixteen, two were killed and eleven were wounded, for the Germans sniped at them as they worked to carry the wounded from the field. During those three days and nights O'Rourke worked unceasingly rescuing the wounded, dressing their injuries under fire and bringing food and water to them. The area in which he worked was continually subjected to the severest shelling and was frequently swept by machine-gun and rifle fire. Several times he was knocked down and partially buried by shell-bursts. Once, seeing a comrade who had been blinded stumbling along in full view of the enemy who were sniping at him, O'Rourke jumped out of the trench and brought him in, being himself heavily sniped at while doing so. Again he went forward about fifty yards in front of our barrage, under very heavy fire from machine-guns and snipers, and brought in another wounded man; and later, when the advanced posts retired to the line, he braved a storm of enemy fire of every description and brought in a wounded man who had been left behind.