When the expected signal came, it was startling in its suddenness. Kenneth had not seen an object fall from the aeroplane, but there was a sharp explosion just beyond the bridge, a cloud of dust, and cries of amazement and fear from the guards. He moved nearer to the bridge. From the direction of the troop train he heard the crackle of rifles. The eyes of the guards were still turned upwards upon the monoplane, which was circling round at a height of three or four thousand feet above the bridge, within range, indeed, but a difficult target. Taking advantage of the excitement of the men, Kenneth had crept through the scrub on the river bank and come beneath the end of the bridge. He had already perceived that the stone arch at each end had been destroyed, but the centre arch was intact, and the gaps had been covered with stout balks of timber on which the railway track was laid. His aim must be to destroy the central arch. With that broken down, to repair the bridge a second time would be a much more difficult matter. Covered now by the bridge, he waded out to the central arch, carrying his apparatus. He had supposed that it would be necessary to hack out with the pick-axe a hole in the masonry large enough to hold the case of gelignite, and the risk of being heard strung his nerves to a high tension. It was with great relief that he discovered a hole already made. Apparently a charge had been laid there by the Belgian engineers, but it had failed to explode, and probably had been removed by the Germans. He lost no time in wedging the case of gelignite into the cavity, attached the detonator, and waded back to the bank. There was now almost continuous rifle fire from the troops, who had alighted from the train and lined up on the track. The incessant noise smothered the whirr of the propeller, but it was clear that Pariset was still absorbing the attention of the Germans. Kenneth crept along up stream, paying out the wire as he went, until he reached the shelter of a dense thicket. Then he made the connection with the battery. Instantaneously there was a deafening roar, the arch collapsed, and the whole bridge fell with a crash into the river. Somewhat breathless, Kenneth remained hidden for a minute. The rifle shots had ceased; there was a confused shouting from the troops; and through it he heard again the hum of the aeroplane. A bomb burst on the ground near the end of the bridge. The fusillade recommenced. Seizing the opportunity, Kenneth quitted his hiding-place, and made the best of his way back across the field, observing that Pariset was still circling round in order to distract the enemy, but rising ever higher. When Kenneth reached the rendezvous Pariset was awaiting him. "Hullo! You’re wounded!" cried Kenneth, noticing that Pariset was grasping his right wrist.