The tramp expressed her gratitude by giving a series of whoops on her siren, and, steadying on her course, headed towards a number of M.L.'s, which, called up by wireless, were hurrying to her aid. The sun was still above the horizon when Derek "cut out" preparatory to descending at the aerodrome. Miles away the sky was stabbed by countless flashes that more than held their own against the glow of departing day, while the air reverberated with the roar of heavy guns. In spite of the volplaning air-craft's rush through the air, and the shriek of the wind, the ceaseless rumble was plainly audible. Ahead, right and left, as far as the eye could see, the lines of flashes continued. A big engagement, not merely a series of local operations, was in progress. The Sergeant-Observer actually grinned in his officer's face, for there is such a thing as a companionship of the air that makes small beer of cast-iron methods of discipline. "We're not too late, after all, sir," he exclaimed through the voice-tube. "They're going it hammer and tongs." Making her distinctive signal, GV 7 circled around the landing-ground until the coast was clear, for there was much aerial activity in progress, machines rising and descending almost ceaselessly. "All clear, sir!" reported one of the battleplane's crew, as a tri-coloured flare rose from the gathering shadows betwixt the hangars. "Right-o!" rejoined Derek. "Down we go." A succession of jerks announced that the battleplane had renewed acquaintance with the earth, although it was the first time as far as the soil of France was concerned. Derek stood up in his "office" and pushed back his goggles. The scene that awaited him was very much like that of an aerodrome in England. There were mechanics hurrying towards him, while in a few moments a couple of flying-officers strolled up. "New 'bus?" enquired one casually. "Just out? What's doing in town?" Daventry did his best to reply to the widely-divergent questions, and dared to ask how things were going out there. "Doing? Heaven only knows!" replied one of the two officers. "Apparently we're doing a sort of fox-trot backwards. 'T anyrate we've orders to pack up before morning. The Boche is, we understand, about twelve miles away, and during the last three days has been pushing on at three miles a day. Come along to the mess and see what's going."