Colter reached the equator of the Missouri, the mouth of the Platte and there met a big party coming upriver, bound for the rich beaver country which the return of Lewis and Clark had publicized. It was commanded by the veteran St. Louis trader Manuel Lisa, the shrewdest mind in the business and by far the most successful bourgeois the American trade was to have during its first period. Lisa had hired George Drewyer as his guide and principal dependence in the new country. He had also hired the John Potts and Peter Wiser who had been with Lewis and Clark, and now he got another member of the great company. For again Colter turned back to the wilderness, and this time he marched into American legendry. Where the Big Horn River empties into the Yellowstone, a site that had been duly recommended by William Clark, Lisa built the first post of the Western fur trade. Thence he sent Colter to find the Blackfeet and bring them in to trade. Without companions Colter made a journey so remarkable that it makes one’s breath catch. His route has been much disputed and will never be confidently established, but he went up the Big Horn and found the Stinking-Water River (more gently the Shoshone in these days) and the neighboring bitumen springs and thermal phenomena that were called “Colter’s Hell” thereafter – and were laughed at by greenhorns back home as a damned amusing lie. He crossed the Divide, the first white man to do so after the expedition, and traveled across part of the more spectacular hell that is now Yellowstone National Park. Before he met the Blackfeet he met their implacable enemies the lcrows and traveled with them. So when the enemies met he had to fight with the Crows, killing some Blackfeet.
Some writers have held that this encounter sealed or perhaps created the murderous hostility to American trappers that the Blackfeet maintained for many years. Probably it was more complex than that, and perhaps a great part of it was the natural belligerence of the Blackfeet who never kept the peace with anyone for very long, not even with themselves, but there is no doubt that the anti-American policy existed. And in the next year and a half Colter helped a good many Blackfeet find the sunset trail.