Colonel Winchester joined them as he was speaking, and listened to the double signal which was repeated later.  But it did not come again, although they waited some time.  Instead they heard, as they had heard all through the night, the occasional swish of the soft snow sliding down the slopes.  But Dick saw that the colonel was uneasy, and that his apprehensions were shared both by Shepard and the mountaineer.

“Do you know how many men these brigands have?” Colonel Winchester asked of Reed.

“I reckon thar are five hundred uv them gorillers,” replied the mountaineer.  “Some uv our people spied on ’em in Burton’s Cove an’ counted ’bout that number.”

Colonel Winchester glanced at his sleeping camp.

“I have three hundred,” he said, “but they’re the very flower of our youth.  In the open they could take care of a thousand guerrillas and have something to spare.  Still in here—­”

He stopped short, but the shrewd mountaineer read his meaning.

“In the mountings it ain’t sech plain sailin’,” he said, “an’ you’ve got to watch fur tricks.  I reckon that when it comes to fightin’ here, it’s somethin’ like the old Injun days.”

“I can’t see how they can get at us here,” said Colonel Winchester, more to himself than to the others.  “A dozen men could hold the exit by the creek, and fifty could hold the entrance.”

Despite his words, his uneasiness continued and he sent for the sergeant, upon whose knowledge and instincts he relied greatly in such a situation.  The sergeant, who had been watching at the other end of the valley, came quickly and, when the colonel looked at him with eyes of inquiry, he said promptly: 

“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!”