And then a thing happened that at least one man saw and fortunately remembered later. Bryan, the trumpeter, with jabbing heels and flapping arms, was tearing back toward the troop at the moment at the top speed of his gray charger, already so near that he was shouting to the sergeant in the lead. By this time, too, that veteran trooper, with the quick sense of duty that seemed to inspire the war-time sergeant, had jumped his little column "front into line" to meet the unseen danger; so that now, with carbines advanced, some thirty blue jackets were aligned in the loose fighting order of the prairies in front of the foremost wagon. The sight of the distant officer and men tumbling hurriedly back and to one side, out of the way presumably of some swiftly-coming peril, acted like magic on the line. Carbines were quickly brought to ready, the gun locks crackling in chorus as the horses pranced and snorted. But it had a varying effect on the occupants of the leading wagon. The shout of "Indians" from Bryan's lips, the sight of scurry on the ridge ahead brought the engineer and aide-de-camp springing out, rifle in hand, to take their manly part in the coming fray. It should have brought Major Burleigh too, but that appropriately named non-combatant never showed outside. An instant more and to the sound of rising thunder, before the astonished eyes of the cavalry line there burst into view, full tear for safety, the uncouth, yet marvelously swift-running leaders of the little herd. The whole dozen came flying across the sky line and down the gentle slope, heading well around to the left of the line of troopers, while sticking to their flanks like red nettles half a dozen young warriors rode like the wind on their nimble ponies, cracking away with revolver or rifle in savage joy in the glorious sport. Too much for Burleigh's nerve was the combination of sounds, thunder of hoofs and sputter of shots, for when a cheer of sympathetic delight went up from the soldier line at sight of the chase, and the young engineer sprang to the door of the ambulance to help the major out, he found him a limp and ghastly heap, quivering with terror in the bottom of the wagon, looking for all the world as if he were trying to crawl under the seat. CHAPTER IV.