The Corps of Discovery, under the command of Meriwether Lewis and William Clark, was the first official expedition through the interior of the North American continent sponsored by the United States. Captain Meriwether Lewis passed Charles Town in Virginia, later renamed Wellsburg, on September 7, 1803, bringing the expedition's keelboat down the Ohio River to rendezvous with William Clark near Louisville, Kentucky. The expedition spent the winter of 1803-04 at a camp near what is today Wood River, Illinois, preparing for the arduous journey to the Pacific Ocean and back. Patrick Gass, whom Lewis considered a man of capacity, diligence, and integrity, volunteered for the expedition while stationed at Fort Kaskaskia in Illinois despite the objections of his superiors. After Sgt. Charles Floyd, the expedition's only casualty, died on 20 August 1804, Gass was elected by the party to replace him as Sergeant in the corps of volunteers for North Western Discovery. Gass later returned to Wellsburg and, at his death in 1870, was the last living member of the Corps of Discovery.