Derek's wound was still bleeding freely. He made no attempt to staunch the flow, knowing that there was a chance of the cut cleansing itself. His old 'bus had practically burnt itself out. The fierce flames were succeeded by a thick, oily smoke that drifted in clouds across the crater and eddied down the slope, as if reluctant to soar and dissolve in the comparatively pure air above. It was with the greatest difficulty that the pilot managed to refrain from coughing. Temporarily the musketry-fire had ceased and comparative silence reigned. Any noise coming from the crater would inevitably betray the presence of a yet-living man to the vigilant Huns. Yet, on the other hand, the smoke was of service. It acted as a screen and prevented the Germans seeing their foes; and behind this pall of smoke fresh British troops were massing for another attack, while the methods adopted for bridging the canal for the passage of the tanks were being carried out at high pressure. Then ensued a tedious period of inactivity. Both British and German guns were firing desultorily, the former putting over heavy stuff, while the Huns contented themselves by "watering" the back-areas with high-velocity shells of medium calibre. Overhead British aeroplanes passed and repassed--big bombing-machines, intent on their ceaseless task of harrying Fritz's lines of communication. The crashed pilot was now almost unmolested. The tic-tac of the German machine-guns had ceased, but, with their customary cunning, the Huns would, after a period of inactivity, suddenly send over a number of bombs. As long as they had the faintest suspicion that somebody was alive in the crater they meant to continue the strafing. A remorseless resentment towards the British airman who had so effectually machine-gunned their trenches urged them to complete their task of wiping out the cause of their discomfiture. Just as likely as not, the moment darkness set in Fritz would dispatch a party to search thoroughly the scene of the biplane's crash. Fervently Derek hoped that the tanks would be in action before night fell. The misty sun sank lower and lower in the western sky. Steadily and stealthily the shadow of the lip of the crater rose higher and higher upon the opposite slope. Evening mists were rising from the dank, unwholesome soil. Then, as the sun set, away to the north-east, and again to the south-west, a steady rumble, and the glare of numerous searchlights and star-shells, betokened considerable activity; while behind the German lines the sky glowered in the light of dozens of burning ammunition-dumps. Notwithstanding the determined resistance offered in this sector of the line, the Germans were preparing for a further retreat and abandonment of ground implacably held by them for more than four long years.