Roque impatiently moved about among the ruins, acting as a sentinel, and occasionally turning to the laboring aviators with muttered insistence for haste. "Hist!" With the chief's sibilant warning the boys softly laid down the tools and motor parts they were handling, and stood at attention. Schneider drew a revolver from his belt. Roque, in crouching attitude, held an ear close to the frozen earth surface, and the others took example. "There's a cavalry troop headed this way," hoarsely whispered Schneider. The pounding of many hoofs, growing louder and louder, was a sound apparent to each listener. Then as a new diversion, out in the open field to the right of the road, down which the horsemen were galloping, rang out the rapid blows of pikes and spades on the ice-covered soil. "They're throwing up kneeling trenches." Schneider had a true ear for war moves. The grating noise of the closing of a gun breech preceded a tense moment. By the shifting of sound it was impressed upon the listeners that the oncoming cavalry had left the road and had swung into the plain on the left. "We'll be between two fires in a minute or so." This from Roque, as he rejoined his companions standing by the aëroplanes. "Give us a precious ten minutes and we need not care," volunteered Henri, who had discovered the defect in the machinery which had brought them down. "Get at it, then," urged Roque. The boys did "get at it" so vigorously that they raised a perspiration, despite the frigid air. "It's all right now," triumphantly announced Billy, hastily repacking the tools. That they had been spared the time required to meet the emergency was due to the fact that the cavalrymen had diverted their course so as to make a sudden frontal charge on the artillerymen from the cover of the ruins. "Now for a move backward," ordered Roque in low tone; "even though the gunners to the right may wear the gray we would have no show for recognition if we bounced up like a flock of partridges." So the aviation party cautiously wheeled the biplanes in the deserted street as far as they could from the supposed line of the coming clash. None too soon were they out of range, for with savage yells the Cossacks rode full-tilt from cover at the German guns and gunners in the shallow trenches. Amidst the roar of desperate conflict the biplanes whizzed away like great arrows. "Some speedy tinkering we did in that ghost town, Mr. Roque?" "Nothing slow," assented Roque, leaning forward to give Billy a pat on the back. "Where away now?" asked the pilot. "Back to the lodge for the night," directed the chief. No such comfort for the boys in the next flight. They were booked for a journey to Przemysl, the vast underground fortress of Galicia, about which the Russian right end was then snapping like the tip of a whip around a sapling, and later surrounded on all sides by the Muscovite forces.