Fort Osage from the west. The "factory" trading post is on the left
|Added to NRHP:||October 15, 1966|
|Designated NHLD:||November 5, 1961|
The Osage in exchange for access to the trading post above the Missouri River in 1808 in the Treaty of Fort Clark ceded all of their lands east of the fort in Louisiana Territory effectively leaving them with a small band of territory on the extreme western border of Missouri.
The fort ceased operations in the 1820s as the Osage in subsequent treaties ceded the rest of their land in Missouri. A replica of the fort was rebuilt on the site in the 1950s.
- high commanding position, more than 70 feet above high-water mark, and overlooking the river, which is here but of little depth
Fort Osage was one of three forts established by the U.S. Army to establish control over the newly acquired Louisiana Purchase territories. Fort Madison was built to control trade and pacify Native Americans in the Upper Mississippi River region. Fort Belle Fontaine near St. Louis controlled the mouth of the Missouri.
William Clark led a team in 1806 back to the site to begin construction of Fort Osage. In 1808 Chouteau negotiated a deal for the fort to be built for the protection of the Osage. The specific terms of the deal noted:
The United States being anxious to promote peace, friendship and intercourse with the Osage tribes, to afford them every assistance in their power, and to protect them from the insults and injuries of other tribes of Indians, situated near the settlements of the white people, have thought proper to build a fort on the right bank of the Missouri, a few miles above the Fire Prairie, and do agree to garrison the same with as many regular troops as the President of the United States may, from time to time, deem necessary for the protection of all orderly, friendly and well disposed Indians of the Great and Little Osage nations, who reside at this place, and who do strictly conform to, and pursue the counsels or admonitions of the President of the United States through his subordinate officers.
In order to get the protection, the Osage ceded all of Missouri east of the fort. The Great Osage were to receive $1,000 and the Little Osage were to get $500.
Fort Osage was abandoned during the War of 1812 because it was not considered to be under threat. Since most of the war's fighting was further east and north, the soldiers there were transferred to different locations. After the war the fort was reoccupied in 1814.
The fort was officially christened "Fort Osage" by Captain Eli Clemson who was in charge of the military garrison. It has also been informally referred to as "Fort Clark" in honor of William Clark who was in charge of Indian Affairs. It was one of the first United States military installations in Louisiana Territory became a major stopping point for visitors traveling the Missouri. Daniel Boone was to visit it in 1814, at the age of 81, while on one of his last hunting trips. Sacagawea and her husband, Toussaint Charbonneau, also stayed at the fort on their way back north to Dakota Territory.
As the Osage ceded more and more of their land a new trading post at Fort Scott, Kansas was established closer to the ancestral villages near the headwaters of the Osage River near Nevada, Missouri and its Osage mission formally ended in 1822.
The fort remained a landmark on the Santa Fe Trail and a transit point for supplies going north. However, by 1836 it had been totally obliterated with its pre-cut wood used by local settlers for building houses and barns. The factory house was the last remaining structure, but burned to the ground, leaving only the rock foundation.
In the 1950s, archeologists searching for the site discovered the foundations of these buildings and rebuilt the Fort as closely as they could. Extensive surveys of the fort, done by William Clark and others, were preserved, making restoration to exact specifications relatively simple. It now stands, overlooking the Missouri River once again. The Fort Osage school district (including Fort Osage High School), which serves northeast Independence and the surrounding area, was named after it.
Fort Osage National Historic Landmark 
Currently the fort is known as Fort Osage National Historic Landmark and has been reconstructed to portray Fort Osage as it was in 1812. Living history demonstrations are given about early 19th century military and civilian life.
The Fort Osage Education Center, opened in November 2007, contains exhibits about the site's geology, 19th century natural history, the Hopewell and Osage native cultures, Lewis and Clark, Fort Osage and the Missouri River.
Fort Osage is owned and operated by Jackson County Parks and Recreation. It is open to the public Tuesday thru Sunday from 9:00am to 4:30pm year round.
- "National Register Information System". National Register of Historic Places. National Park Service. 2007-01-23.
- "Fort Osage". National Historic Landmark summary listing. National Park Service. Retrieved 2008-06-28.
- Fort Osage - National Park Service
- Prucha, Francis P. (1964) A Guide to the Military Posts of the United States 1789–1895. State Historical Society of Wisconsin, Madison.; also Prucha, Francis P. (1969) The Sword of the Republic: The United States Army on the Frontier 1783–1846. Macmillan, New York.
- Treaty of Fort Clark
- Junius P. Rodriguez (2002) The Louisiana Purchase: A Historical and Geographical Encyclopedia p. 270, Clio, Santa Barbara, CA