Florida to Spain. British inhabitants of Florida had to leave the province within 18 months unless they swore allegiance to Spain. In 1811, surveyor George J. F. Clarke platted the town of Fernandina, named in honor of King Ferdinand VII of Spain by the governor of the Spanish province of East Florida, Enrique White.
With the approval of President James Madison and Georgia Governor George Mathews in 1812-1813, insurgents known as the "Patriots of Amelia Island" seized the island. After initially raising the Patriot flag, they replaced it with the flag of the United States. American gunboats under the command of Commodore Hugh Campbell maintained control of the island until Spanish pressure forced their evacuation in 1813. The Spanish erected Fort San Carlos on the northwest end of the island in 1816.
Gregor MacGregor, a Scottish-born soldier of fortune, led an army of only 150 men including recruits from Charleston and Savannah, some War of 1812 veterans, and 55 musketeers in an assault of Fort San Carlos on June 29, 1817. The commander, Francisco Morales, struck the Spanish flag and fled. MacGregor raised his flag, the "Green Cross of Florida", a green cross on a white ground, over the fort and proclaimed the "Republic of the Floridas".Spanish soldiers forced MacGregor's withdrawal, but their attempt to regain complete control was foiled by American irregulars organized by Ruggles Hubbard and former Pennsylvania congressman Jared Irwin. Hubbard and Irwin later joined forces with the French-born pirate Louis Michel Aury, who laid claim to Amelia Island supposedly on behalf of the Republic of Mexico.Aury surrendered the island to U.S. forces on December 23, 1817, and President James Monroe vowed to hold it "in trust for Spain". This episode in Florida's history became known as the Amelia Island Affair.
Although angered by U.S. interference at Fort San Carlos, Spain ceded Florida in 1821. The Adams-Onis Treaty officially
