Fort Mose Historic State Park Fort Mose Historic State Park ( originally known as Gracia Real de Santa Teresa de Mosé ) is a U . S . National Historic Landmark ( designated as such on October 12 , 1994 ) , located two miles north of St . Augustine , Florida , on the eastern edge of a marsh . The original site of the fort was uncovered in a 1986 archeological dig . The site is now a Florida State Park , administered through the Anastasia State Recreation Area . Fort Mose was designated a National Historic Landmark in 1994 and is the " premier site on the Florida Black Heritage Trail . " The fort has also been known as Fort Moosa or Fort Mossa . Fort Mose ( pronounced " Moh - say " ) was the first free black settlement legally sanctioned in what would become the United States . The community began when Florida was a Spanish territory . Historical background . As early as 1687 , the Spanish government had begun to offer asylum to slaves from British colonies . In 1693 , the Spanish Crown officially proclaimed that runaways would find freedom in Florida , in return for Catholic conversion and a term of four years of service to the Crown . In effect , Spain created a maroon colony as a front - line defense against English attacks from the north . Spain also intended to destabilize the plantation economy of the British colonies by creating a free black community that would serve as a destination for slaves seeking escape and refuge . Fort Mose . Incoming freedom seekers were recognized as free , taken into the Spanish militia , and placed into service at the Gracia Real de Santa Teresa de Mosé military fort north of St . Augustine , which was established in 1738 by the Colonial Governor , Manuel de Montiano . The military leader at the fort was a Creole man of African origin , who was baptized as Francisco Menendez by the Spanish Fort Mose ( pronounced " Moh - say " ) was the first free black settlement legally sanctioned in what would become the United States . Word of the settlement reached the South Carolina and Georgia to the north , attracting escaping slaves . It helped to set off the Stono Rebellion in September 1739 , led by slaves " fresh from Africa " in South Carolina , who were more likely to revolt . During the Stono revolt , several dozen blacks tried unsuccessfully to reach Spanish Florida . In 1740 , British forces , led by James Oglethorpe of Georgia , attacked and destroyed the fort in the Siege of Fort Mose . During the siege , a force consisting of Spanish troops , Indian auxiliaries , and free black militiamen counterattacked Oglethorpe ' s troops , forcing them back to Savannah . Because the fort was destroyed , its inhabitants relocated to St . Augustine , where they stayed until Fort Mose was rebuilt in 1752 . After East Florida was ceded to the British in the Peace of Paris of 1763 most of the inhabitants , including many black militia troops , migrated to Cuba with the evacuating Spanish . A haven for escaped slaves from the British colonies to the north , Fort Mose is considered the " premier site on the Florida Black Heritage Trail . " It is also a precursor site of the Underground Railroad . This was the network in the antebellum years by which slaves escaped to freedom , most often to the North and Canada , but also to the Bahamas and Mexico .