The Blackfeet remained firm enemies of the invading trappers and fur-hunters. John Colter's adventures were the beginning of a long and bitter war. The Crows made friends with the white men, and only stole their horses and traps and other "plunder;" but to a Crow this was no crime. The Sioux and Cheyennes and Arapahos and Utes frequently declared that their hearts were good. The Blackfeet never softened. They were many in number, and proud and scornful, and did not stoop even to pretend friendship.
The Three Forks region became known as one of the most dangerous places in the beaver country. All the Upper Missouri River, from the Yellowstone River on, was dangerous by reason of the widely roaming Blackfeet.
Of course, the American trapper and trader did not stay away, on this account. Manuel Lisa and others had formed the Missouri Fur Company, in 1809. In 1822 the Rocky Mountain Fur Company was organized, at St. Louis, and advertised for "one hundred young men to ascend the Missouri River to its source, there to be employed for one, two, or three years," trapping.
It proved to be a famous company. It had on its rolls Jim Bridger, Kit Carson, Jedediah Smith the Knight in Buckskin, the Sublette brothers, Jim Beckwourth the French mulatto who lived with the Crows as chief, and scores of others, mainly young men, genuine Americans of both French and Anglo-Saxon blood. Its career did not cease until the summer of 1834.
The two men who organized the company were General William Henry Ashley of the Missouri militia, and first lieutenant-governor of the State; and Major Andrew Henry who had helped to found the Missouri Fur Company and now was mining for lead in Washington County southwest of St. Louis.
Major Henry already had served in the Blackfeet country. He was there at the Three Forks in the spring of 1810, when five trappers had been killed or captured and John Colter had decided to pull out. Next, George Drouillard, who had been a hunter with the Lewis and Clark party (another of John Colter's old companions), and whose father Pierre Drouillard had rescued Simon Kenton from the Shawnees, was killed while fighting bravely. Finally the Blackfeet had driven all the trappers from that region. Major Henry led his remaining men west across the mountains, to the Snake River in Idaho. There on Henry Fork he built a trading-post. It was the first American post west of the Rocky Mountains.