Somewhere behind him on the road, a motor bike roared through the mist, and then to the southward a shell crashed not a thousand yards from the ’drome, and the echo of it thumped off across the fields. Darlington jumped and stared at the mushroom of greasy black smoke. A moment more--a moment now. Paterson reached over and tapped Darlington’s sleeve. “Keep your guns warm, old boy.” Darlington nodded fiercely. The major climbed into his cockpit and a mechanic leaped to the propeller. The engine coughed once and the propeller snapped back. The mechanic leaped at it again. It spun down and melted into a circle of pale light. Everyone was climbing in. Hoyt flicked his cigarette away sharply and put a leg up into his stirrup. They were taxi-ing out into the open ground, with the mechanics running after them. Presently they could see the road. Paterson stared at it in amazement. It was brown and crawling with lorries and troops. Something had happened! A Flight, with the major, sang off across the ground and took the air together in a climbing turn. B Flight waited a brief second and followed. Out of the corner of his eye, Paterson could see the mess sergeant climbing up on the lorry seat beside Harbord, the equipment officer. Then Hoyt waved his hand. Mechanics yanked at the chock ropes and waved them off. They blipped their motors and raced out after Hoyt. At five hundred feet they took the roof in the lacy fringe of the low clouds. Bad, very bad, Paterson thought. He ran his thumb across the glass face of his altimeter and his globe became wet with the beaded moisture. He could hardly see Darlington’s tail. Ahead of them the clouds were a trifle higher. Hoyt led them up and turned northward. Murder to cross the line at that height, with the barrage on. Darlington was lagging a bit. Afraid of the clouds. He dived on Darlington’s tail and closed him up on Number 3. Darlington glanced back at him and ducked his head. Hoyt was circling back now in a broad sweep. Over there somewhere was Cambrai. He looked up for an instant just in time to see the underside of a huge plane sweep over him. He ducked at the sight of the black crosses, but the plane was gone before he could whip his Lewis gun into action. Almost immediately one corner of his windshield ripped away and the triplex glass blurred with a quick frosting of a thousand cracks. He cursed into the roar of his motor and kept on. They were higher now, but the visibility was frightful--like flying in a glass ball that had been streaked with thick dripping soapsuds. Here a glimpse and a rift that closed up as soon as you looked; there a blank wall, tapering into tantalizing shreds that you couldn’t quite see beyond. He fidgeted in his cockpit and turned his head from Hoyt, below him, to the gray emptiness behind. Nothing.