1804, when Missouri became part of the United States following the Louisiana Purchase. He was appointed captain of the local militia. Because Boone's land grants from the Spanish government had been largely based on oral agreements, he again lost his land claims. In 1809, he petitioned Congress to restore his Spanish land claims, which was finally done in 1814. Boone sold most of this land to repay old Kentucky debts. When the War of 1812 came to Missouri, Boone's sons Daniel Morgan Boone and Nathan Boone took part, but by that time Boone was much too old for militia duty. Although Boone reportedly vowed never to return to Kentucky after moving to Missouri, stories (possibly folk tales) were told of him making one last visit to Kentucky to pay off his creditors. American painter John James Audubon claimed to have gone hunting with Boone in Kentucky around 1810. Years later, Audubon painted a portrait of Boone, supposedly from memory, although skeptics noted the similarity of his painting to the well-known portraits by Chester Harding. Some historians believe Boone visited his brother Squire near Kentucky in 1810 and have accepted the veracity of Audubon's account.Boone spent his final years in Missouri, often in the company of children and grandchildren. He continued to hunt and trap as much as his health and energy levels permitted, intruding upon the territory of the Osage tribe, who once captured him and confiscated his furs. In 1810, at the age of 76, he went with a group on a six-month hunt up the Missouri River, reportedly as far as the Yellowstone River, a round trip of more than 2,000 miles. He began one of his final trapping expeditions in 1815, in the company of a Shawnee and Derry Coburn, a slave who was frequently with Boone in his final years. They reached Fort Osage in 1816, where an officer wrote, "We have been honored by a visit from Col. Boone... He has taken part in all the wars of America, from Braddock's war to the present hour," but "he prefers the woods, where you see him in the dress of the roughest, poorest hunter." Death and burial Boone died on September 26, 1820, at his son Nathan Boone's home on Femme Osage Creek, Missouri. He was buried next to Rebecca, who had died on March 18, 1813. The graves, which were unmarked until the mid-1830s, were