A young Spaniard, Manuel Lisa, engaged in the fur trade in St. Louis, and influenced by reports of the abundance of beaver on the upper Missouri, had determined to explore the possibilities of extending his operations in that hitherto unexploited region. Accordingly, he organized a brigade and set forth up river. Colter met the party, and was persuaded by Lisa to join him. Lisa, a shrewd trader, was not a frontiersman. He recognized in Colter exactly the type of man he needed, and quite probably the inducements he offered were considerable. Yet, to a man of Colter’s stamp, the financial gain possible was secondary to the prospect of further opportunity for adventure. We can surmise that Lisa experienced little difficulty in influencing the young and venturesome trapper to turn his back again on the doubtful attractions of the settlements. It was late in November of that year, 1807, before Lisa selected a site for his trading post, at the confluence of the Yellowstone and Big Horn Rivers, in what is now south-central Montana. Construction of the post was begun immediately. Lisa named it Fort Raymond, after his son, but it was more generally known as Manuel’s Fort. It was Lisa’s objective, not only to trap, but to engage in trade with the Indians, and to learn as much as possible about the trapping territory to the west. Of his men, Colter was the best suited to seek out the tribesmen, encourage them to trade at the post, and survey the lands with an eye to its productivity in fur. Thus Lisa instructed him, outfitted him, and sent him forth. It could not have been earlier than late November when Colter set out. His equipment must have been meager; snowshoes, his gun, ammunition, a blanket or robe, and little or no food, since he would have intended to “live off the land” and his pack would likely not have exceeded 30 pounds, including “geegaws” for the Indians he encountered. His exact route has long been a matter for conjecture among historians. He was to venture into country unknown to any other than the Indians, he carried no maps, he followed what must have appeared to him to be the route of least resistance, insofar as he could judge the terrain he traversed. He, from force of circumstance, must have followed the watercourses and game trails, sought the lowest mountain passes he could find, pursuing a devious course which led him to the south and west.