William H. Thomas was the surgeon to the Missouri Fur Company's party, that, in 1809, ascended the Missouri River to the Mandan Villages. The purpose of their expedition, besides pursuing the fur trade, was to return Chief Sheheke to his village. Shehek e had accompanied Lewis and Clark on their return trip to Washington, and had been promised safe return to his people. Lewis made an arrangement with the Missouri Fur Co., under Pierre Chouteau Sr., to escort Sheheke. Manuel Lisa and Thomas James were also with this expedition. James left an account of the trip, in his Three Years among the Indians and Mexicans. Thomas' journal includes an account of Colter's run.
The journal of Dr. Thomas was originally published in two parts in the Missouri Gazette, St. Louis, November 30 & December 1809; and was reprinted in the Pittsburgh Gazette, July 6 & 13, 1810. The two parts were published together in the Missouri Historical Society Bulletin, 20, no. 3 (April 1964): 182-92, Donald Jackson, ed. It has recently been reprinted in News of the Plains and Rockies 1803-1865, compiled by David A. White, The Authur H. Clark Company, Spokane, WA, 1996.