The year 1840 can be said to mark the formal demise of the Rocky Mountain fur trade, for in that year was held the fifteenth and last of these great conclaves of the wilderness, the trapper’s rendezvous on Horse Creek of the Green River. It also marks the end of an epoch in the history of Jackson’s Hole. The main chronicler of this fateful year was the Belgian, Pierre-Jean De Smet, a Jesuit priest who accompanied the American Fur Company’s last expedition to the mountains so that he might survey the prospects for a Catholic mission among the Flathead Indians. This was the beginning of a series of epic pilgrimages to the Far West which were to make him one of the dominant figures in American frontier history. Andrew Drips headed the supply train. Also present were several Protestant missionaries and “the first avowed Oregon emigrant,” Joel P. Walker, and his wife and five children. On April 30, the caravan left Westport, Missouri, and, after two months of traveling over the Great Plains in the midst of vast buffalo herds, it reached its destination. Writes Father De Smet: On the 30th [June] I came to the rendezvous, where a band of Flatheads, who had been notified of my coming, were already waiting for me.... On the 4th of July, I resumed my travels, with my Flatheads; ten brave Canadians also chose to accompany me.... Three days we ascended Green river, and on the 8th we crossed it, heading for an elevated plain which separates the waters of the Colorado from those of the Columbia.... On leaving this plain, we descended several thousand feet by a trail and arrived in Jackson’s Hole [Jackson’s Little Hole].... Thence we passed into a narrow and extremely dangerous defile, which was at the same time picturesque and sublime.... On the 10th, after crossing the lofty mountain, we arrived upon the banks of Henry’s Fork [Snake River], one of the principal tributaries of Snake [Columbia] river. The mass of snow melted during the July heat had swollen this torrent to a prodigious height. Its roaring waters rushed furiously down and whitened with their foam the great blocks of granite which vainly disputed the passage with them. The sight intimidated neither our Indians nor our Canadians; accustomed to perils of this sort, they rushed into the torrent on horseback and swam it. I dared not venture to do likewise. To get me over, they made a kind of sack of my skin tent; then they put all my things in and set me on top of it. The three Flatheads who had jumped in to guide my frail bark by swimming, told me, laughing, not to be afraid, that I was on an excellent boat. And in fact this machine floated on the water like a majestic swan; and in less than ten minutes I found myself on the other bank, where we encamped for the night.