"Fort Bellefontaine was the first United States military installation west of the Mississippi in the new Louisiana Territory."
"Located on the south bank of the Missouri River, in present-day Missouri, Fort Bellefontaine was first a Spanish military post. After the Louisiana Purchase, by a treaty made between the United States Government, signed by William H. Harrison and representatives of the Native American Sac and Fox tribes (on November 3, 1804), the fort became a fur trading post of the United States Government. Rudolf Tiller served as factor and Col. Thomas Hunt served as first in command."
"The trading post was discontinued after 1808, and from 1809 to 1826 the facility served as a United States military fort. During that time period, from about 1809 to 1815, the fort served as the headquarters of the Department of Louisiana, and was the regional Army headquarters during the War of 1812. Its sister forts were Fort Osage along the Missouri near modern Kansas City, which controlled trade with western Indians; and Fort Madison in what is now Iowa, which controlled trade of the Upper Mississippi."
"Lewis and Clark's Corps of Discovery expedition (1804-1806) spent the first night of their expedition on an island opposite Cold Water Creek and their last night two years later at the fort, which had been established in their absence. Other major expeditions left from this site betweem 1805 and 1819 to explore the newly acquired Louisiana Territory. Until it was replaced by Jefferson Barracks in 1826, Fort Belle Fontaine was an important gathering place in the wilderness for officers and enlisted men, Native American, French, Spanish and American settlers, trappers and traders, and the local businessmen and farmers who supplied the fort with necessities."
Today it is a scenic park and is open to the public.