fort”, remained occupied by more than a thousand former soldiers of the British Royal and Colonial Marines, escaped slaves, and various indigenous peoples. It had become a magnet for escapees and was seen as a threat to the property rights of American enslavers, even a potential source of insurrection by enslaved people. Jackson ordered Colonel Duncan Clinch to capture the fort in July 1816. He destroyed it and killed many of the garrison. Some survivors were enslaved while others fled into the wilderness of Florida. In addition, White settlers were in constant conflict with Native American people collectively known as the Seminoles, who straddled the border between the U.S. and Florida. In December 1817, Secretary of War John C. Calhoun initiated what would be called the First Seminole War by ordering Jackson to lead a campaign "with full power to conduct the war as he may think best". Jackson believed the best way to do this was to seize Florida from Spain once and for all. Before departing, Jackson wrote to President James Monroe, "Let it be signified to me through any channel ... that the possession of the Floridas would be desirable to the United States, and in sixty days it will be accomplished." Jackson invaded Florida, captured the Spanish fort of St. Marks, and occupied Pensacola. Seminole and Spanish resistance was effectively ended by May 1818. He also captured two British agents, Robert Ambrister and Alexander Arbuthnot, who had been working with the Seminoles. After a brief trial, Jackson executed both of them, causing a diplomatic incident with the British. Jackson's actions polarized Monroe's cabinet. The occupied territories were returned to Spain. Calhoun wanted him censured for violating the Constitution, since the United States had not declared war on Spain. Secretary of State John Quincy Adams defended him as he thought Jackson's occupation of Pensacola would lead Spain to sell Florida, which Spain did in the Adams–Onís Treaty of 1819. In February 1819, a congressional investigation exonerated Jackson, and his victory was instrumental in convincing the Seminoles to sign Treaty of Moultrie Creek in 1823, which surrendered much of their land in Florida. Presidential aspirations Election of 1824 In 1819, mismanagement by the Second Bank of the United States created a financial panic that sent the U.S. into its first prolonged financial depression. The United States reduced its military and Jackson was forced to retire from his major