A battalion in mass formation moving by the side of a straight stretch of canal afforded fair sport. Derek dived almost perpendicularly, with engines "all out" until within two hundred feet from the ground, then, flattening out, made straight for the head of the field-greys. At the sight of this startling apparition the Boches were instantly thrown into a panic. They broke ranks and fled. Barred on the right by the canal, they were compelled to surge in a disorderly mob across absolutely open ground. Impeding each other, literally falling over one another, the wretched Boches were at the mercy of the swift battleplane. Machine-guns and bombs both took heavy toll, hardly a shot being fired in return. Not once, but many times, did GV 7 swing round and return to the attack, until the thoroughly terrified survivors took refuge in isolated shell-holes until the immediate danger was past. Then back to the almost deserted aerodrome Derek flew, replenished petrol and trays of ammunition, and returned to the fray. He was but one pilot of hundreds engaged upon the same errand. Truly the magnificent work was being accomplished at heavy cost, but temporarily at least the rush was stayed, and the much-harassed infantry--the troops who invariably bear the brunt of both attack and defence--were able to take breathing-space. "We're holding the blighters all right, sir," reported the Wing-Commander to the General of the Division. "Quite so," rejoined the other dryly. "Unfortunately, the line is bending both on our right and left flanks. 'Fraid we'll have to give the Boche a little more ground." For three more days the retirement, under excessive pressure, continued; and during the whole of that time massed squadrons of air-craft were continuously in the air--bombing, machine-gunning, undertaking reconnaissance work, and altogether making things very uncomfortable for the Huns. But there were undoubted evidences that the greatly-advertised Boche offensive was slowing down. Already the advance through Noyon towards Paris was an admitted failure, and both British and French, assisted by small American forces, were preparing for the gigantic counter-attack. Fritz had shot his bolt and had missed his target. CHAPTER VIII The Hun Bomber The Flight-Sergeant surveyed GV 7 dispassionately. It was part of his job to condemn unserviceable machines, and the frequency of having to do it bored him. "It's a wonder you got back, sir," he reported. "Why the motors didn't konk out puzzles me, and there's hardly a strut that's perfect. No, sir; I can't pass her. May as well set her on fire and have done with it."