Whether the shot crippled the pilot of the leading pursuer, or whether it was the menace of the heavy howitzers on the German frontier, which was now of short approach--the French flyers suddenly ceased to be aggressive, and with a parting salute of rifle practice, turned back toward their mountain station, while the German machines dashed across the line of safety. Upon landing Billy indulged in a sort of war dance around his chum. "Thought you were gone that time, sure, Buddy," he cried, "and it was simply great the way you pulled out of the hole." "I guess I was stunned for a minute, as though somebody had hit me with a hammer," explained Henri, "but when I found the controls were still working, it was a bracer, I tell you. And if there isn't a cool head" (nodding toward Renos, who was inspecting his wounded wrist) "I never saw one. He stretched his arms over me ready to take hold if I failed to rally, and did it as a matter of course. Not a tremble about him, either." "What do you think of the No. 3's now, boys?" queried Roque, when he had dispatched Renos in search of a surgeon. "They're dandies, all right," promptly agreed the happy pilots. "They will do to hunt trouble with, anyhow," laughed the secret agent, who was immensely pleased with the flying achievements of the day. Roque, pluming himself with the idea that, though he did not hold Ardelle when he had that artful dodger under his thumb, he had at least chased his rival out of the empire; and, having also eased his mind as to the report of a new element in the Alsace campaign, he was impatient in his preparation for departure. Master of detail though he was, the big moves only appealed to him. A great battle was raging at Soissons, on the Aisne river, in France, and Roque had in mind an aërial journey north, and quick flight across the border to the scene of the fierce artillery duel, following the line of march of the mighty force under General von Kluck. The crippled Renos was replaced in the observer's perch by an aviator known as Schneider, a very daredevil, and who was at first inclined to doubt that the boy with whom he was paired had sufficient skill and courage to pilot a military biplane in an active war zone. Henri very quickly convinced the doubter that he was very much older than he looked when it came to the fine points of aëroplaning, and, too, that when there was an emergency demand for "sand" the youngster had plenty to spare. Schneider had additional assurance of capacity when he was advised that both of the lads carried Roque's indorsement of efficiency.