Not a single animal was left for the garrison or the trappers upon which to give chase. The Indians, who have but little sense of right and wrong, might well exult in their achievement. Without the loss of a single man, and even without receiving a wound, they had taken from beneath the very walls of the fort, its whole herd, leaving the garrison powerless to pursue. The loss was very severe to the trappers. Without their horses and mules, they could do nothing. It only remained for them to wait for the return of Mr. McCoy and his party, who had promised, after visiting Fort Walla Walla, to rendezvous at Fort Hall. The Blackfeet Indians were at that time, forty years ago, the terror of the whole region. It is said that the warlike tribe numbered thirty thousand souls. Of course there could not have been any very accurate estimate of the population. Not long after this the small-pox prevailed, with awful fatality. One half of the tribe perished. The dead were left unburied, as the savages endeavored to flee in all directions from the fearful pestilence. A month passed slowly away before Mr. McCoy with his party reached the fort. Very opportunely he brought a fresh supply of animals; having purchased a number at Fort Walla Walla. The united band returned to the Green river. Here Mr. Carson joined a party of one hundred trappers who, in their strength, were to plunge into the very heart of the Blackfeet country, on the Yellowstone river. Arriving at the region where they were to set their traps, they divided into two companies of fifty men each. It was necessary to be always armed and on the alert, ready to repel any sudden attack. The duty of one company was to explore the streams in search of beavers and game for food. The other party guarded the camp, dressed, rudely tanned, and packed the skins, and cooked the food. The trappers were so strong, that they not only went where they pleased, but they were eager to come in contact with the savages, that they might pay off old scores. They were, however, not molested. Not an Indian crossed their path. They subsequently learned, as a solution of the mystery, that at that time the small-pox was making dreadful ravages. Thousands were dying and it was feared the whole tribe would perish. The Indians in their terror, had secluded themselves in the remotest solitudes. Winter was now approaching, with its freezing gales, its drifting snows, its icy streams. It was necessary to find winter quarters for two or three months. The region, drained by the Yellowstone and its tributaries, extends over thousands of square miles. In one portion of the territory there was a mountainous region inhabited by the Crow Indians. As they were the deadly foe of the Blackfeet tribe, they were disposed to cultivate friendly relations with the whites, and to enter into an alliance with them.