"Yes, sir; I think there's mischief a-foot. I can't rightly make out where it's going to be started, but I can hear it, smell it an' feel it. It's like waitin' in a dip on the prairies for a rush by the wild Sioux or Cheyenne horsemen. The signs seem to come through the air." Dick's oppression increased. A mysterious danger was the worst of all, and his nerves were on edge. Think as he might, he could not conceive how or where the attack would be made. The only sound in the valley was the occasional stamp of the horses in the woods and behind the windrows. The soldiers themselves made no noise. The steps of the sentinels were softened in the snow, and the fires, having sunk to beds of coals, gave forth no crackling sounds. He stared down the gap, and then up at the white world of walls circling them about. The sky seemed to have become a more dazzling blue than ever, and the great stars with the hosts of their smaller brethren around them gleamed and quivered. The stamp of a horse came again, and then a loud shrill neigh, a piercing sound and full of menace in the still night. "What was that?" exclaimed the sergeant in alarm. "A horse does not neigh at such a time without good reason!" And then the storm broke loose in the valley. There was a series of short, fierce shouts. Torches were suddenly waved in the air. Many horses neighed in the wildest terror and, all of them breaking through the forest and windrows, poured in a confused and frightened stream toward the entrance of the valley. Then the experience of the sergeant in wild Indian warfare was worth more than gold and diamonds. He knew at once what was occurring and he shouted: "It's a stampede! There have been traitors here, and they've driven the horses with fire!" "And maybe some of them have managed to slip down the mountain side!" said Shepard. It was well for them all that they were men of decision and supreme courage. The terrible tumult in the valley was increasing. The horses, a stampeded mass, were driving directly for the entrance. Only one thing could stop them and that the guards then did. They snatched many burning brands from the nearest fire and waved them furiously in the face of the frightened herd, which turned and ran back the other way, only to be confronted by other waving brands that filled them with terror. Then the horses, instinctively following some leader, turned again and ran back to their old places among the trees and behind the windrows, where they stood, quivering with terror. A crackling of rifles had begun before the horses were driven back, and bullets pattered in the valley. Dark figures appeared crouched against the slopes, and jets of fire ran like a red ribbon upon the white of the snow. "The gorillers!" cried Reed. "They've crep' over the ridges, spite uv all our watchin'."