Battle of Negro Fort The Battle of Negro Fort was an 1816 military engagement in which forces of the United States attacked African - American militia and their native American allies in the frontier of northern Spanish Florida . It was the first major battle of Seminole Wars period and marked the beginning of General Andrew Jackson ' s Conquest of Florida . Background . In 1814 , during the War of 1812 , the British Royal Marines established what was known as the Negro Fort on Prospect Bluff along the Spanish side of the Apalachicola River . The garrison initially included around 1 , 000 Britons and several hundred African - Americans who were recruited as a detached unit of the Corps of Colonial Marines , with a strength of four infantry companies . Shortly after the end of the war in 1815 , the British paid off the Colonial Marines , withdrew from the post and left the black population in occupation . Over the next few years the fort became a colony for escaped slaves from Pensacola and Georgia . By 1816 over 800 freedmen and women had settled around the fort , there were also friendly natives in the area . Following the construction of Fort Scott on the Flint River by Colonel Duncan Lamont Clinch of the United States Army , Andrew Jackson decided that to resupply the post , they would have to use the navy to transport goods via the Apalachicola through the sovereign territory of Spain without their permission . During one of these resupply missions , a party of sailors from gunboat s 149 and 154 stopped along the river near Negro Fort to fill their canteens with water . While doing so , the garrison of the fort was attacked and all but one of the Americans were killed . In response Andrew Jackson requested permission to attack the fort , they then dispatched gunboats to reduce Negro Fort . Secretary of State John Quincy Adams justified the attack and subsequent seizure of Spanish Florida by Andrew Jackson as national " self - defense , " a response to alleged Spanish and British complicity in fomenting the " Indian and Negro War . " Adams even produced a letter from a Georgia planter complaining about " brigand Negroes " who made " this neighborhood extremely dangerous to a population like ours . " ( Fort Negro was a symbol of slave insurrection ! ) Southern leaders worried that even a small , impoverished island of rebel slaves in the Caribbean or a parcel of Florida land occupied by a few hundred blacks could threaten the institution of slavery . Battle . As the American expedition drew near the fort on July 27 , 1816 , black militiamen had already been deployed and began skirmishing with the column before regrouping back at their base . At the same time the gunboats under Master Loomis moved upriver to position for a siege bombardment . Negro Fort was occupied by about 330 people during the time of battle . At least 200 were freedmen , armed with ten cannon s and dozens of musket s . They were accompanied by thirty or so Seminole and Choctaw warriors under a chief . The remaining were women and children , the families of the black militia . Before beginning an engagement General Gaines first requested a surrender , the leader of the fort was an African named Garson and he refused . Garson told Gaines that he had orders from the British military to hold the post and at the same time raised the Union Jack and a red flag to symbolize that no quarter would be given . Negro Fort was considered heavily defended by the Americans so after forming positions around one side of the post , the navy gunboats were ordered to start the bombardment . After this the defenders opened fire with their cannons but they were not experienced artillerymen and thus were not effective . It was daytime when Master Jairus ordered his gunners to open fire , after only five to nine rounds of hot shot , a cannon ball entered the fort ' s powder magazine . The ensuing explosion was massive and destroyed the entire post . Almost all of the occupants were killed or wounded and just after the American column and the Creeks charged and captured the surviving defenders . General Gaines later said that the " explosion was awful and the scene horrible beyond description . " There apparently were no American casualties . Aftermath . Garson was executed by firing squad because of his responsibility for the Watering Hole Massacre and the Choctaw Chief was handed over to the Creeks who killed and scalped him . The survivors were taken prisoner and placed into slavery under the claim that Georgia slaveowners had owned the ancestors of the prisoners . Neamathla , a leader of the Seminole at Fowlton , was angered by the death of some of his people at Negro Fort so he issued a warning to General Gaines that if any of his forces crossed the Flint River , they would be attacked and defeated . The threat provoked the general to send 250 men to arrest the chief in November 1817 but a battle arose and it became the official opening engagement of the First Seminole War .