Sublette was among the mountain men who journeyed into the Rocky Mountains and other
unorganized territories, which were often economically controlled by the joint British-Canadian fur companies of
Hudson's Bay Company and
North West Company. Both companies competed against the activities of the
American Fur Company, founded by
John Jacob Astor, who created a monopoly in the
American West before 1830. In 1823, William was recruited in St. Louis by
William Henry Ashley as part of a fur trapping contingent, later referred to as Ashley's Hundred. That was the beginning of a new strategy for conducting the fur trade in response to a change in United States law in 1822. Liquor had been one of the principal currencies traded to
Native Americans; such trafficking had been made illegal. The new scheme set up a
trapper's rendezvous, a
teamster-drover team operating the freight bringing in supplies and returning with furs, and a corps of trappers making their circuit through the year to traps they had set as team members. By 1826, Sublette acquired Ashley's fur business, along with
Jedediah Smith and
David Edward Jackson. By the mid-1830s, his brother Milton joined as one of five men who bought the
Rocky Mountain Fur Company from William and his partners. Sublette retired from trapping after being wounded at the Rendezvous of 1832 in the
Battle of Pierre's Hole. Some accounts said that he had caused the conflict. After recuperating for over a year back in St. Louis, Sublette returned to the uplands and founded Fort William, in the foothills east of the
South Pass. The fort commanded the last eastern stream crossing at the foot of the last ascent to the floor of South Pass. That was the only route readily navigable by wagons over the
Continental Divide. He sold Fort William to the American Fur Company, which renamed it Fort John. After the
U.S. Army took it over, it was renamed as
Fort Laramie. Sublette retired to St. Louis, where he died in 1845. He was buried at
Bellefontaine Cemetery in northern St. Louis. ==Legacy ==