While Astor's ambition led him to aim at controlling the fur trade in the United States, the fact that the western posts, such as Detroit and Michilimackinac, had not been surrendered to the United States till after Jay's treaty, had allowed the British traders of these and other posts of the West to strengthen themselves. Such daring traders as Murdoch Cameron, Dickson, Fraser, and Rolette could not be easily beaten on the ground where they were so familiar, and where they had gained such an ascendancy over the Indians. The Mackinaw traders were too strong for Astor, and the hope of overcoming them through the agency of the "American Fur Company," which he had founded in 1809, had to be given up by him. What could not be accomplished by force could, however, be gained by negotiation, and so two years afterward, with the help of certain partners from among the Nor'-Westers in Montreal, Astor bought out the Mackinaw traders (1811), and established what was called the "South-West Company." During these same years, the St. Louis merchants organized a company to trade upon the Missouri and Nebraska Rivers. This was known as the Missouri Company, and with its 250 men it pushed its trade, until in 1808, one of its chief traders crossed the Rocky Mountains, and built a fort on the western slope. This was, however, two years afterward given up on account of the hostility of the natives. A short time after this, the Company passed out of existence, leaving the field to the enterprising merchant of New York, who, in 1810, organized his well-known "Pacific Fur Company." [Illustration: CASANOV. Trader and Chief.] During these eventful years, the resourceful Astor was, with the full knowledge of the American Government, steadily advancing toward gaining a monopoly of the fur trade of the United States. Jonathan Carver, a British officer, had, more than thirty years before this, in company with a British Member of Parliament named Whitworth, planned a route across the continent. Had not the American Revolution commenced they would have built a fort at Lake Pepin in Minnesota, gone up a tributary of the Mississippi to the West, till they could cross, as they thought would be possible, to the Missouri, and ascending it have reached the Rocky Mountain summit. At this point they expected to come upon a river, which they called the Oregon, that would take them to the Pacific Ocean.