This fort - known as "Negro fort" was built by the British in 1814, on Prospect Bluff, overlooking the Apalachicola River. The remote area of Spanish Florida was already a haven for escaped slaves from the United States and Spanish colonies, who lived and intermixed with the local native Americans, which was part of the formation of the ethnic group known as the Seminole today.
On the arrival of the British during the course of the Anglo-American War of 1812, and an offer of freedom for any slave who fled their US masters to the British, the fort rapidly became a centre of anxiety for southern Americans, and when the Treaty of Ghent ended the Anglo-American war, the British commander Sir Edward Nicolls (who, in a world-wide career, fought in no less than 107 actions) nonetheless ensured that the fort was left stocked when he evacuated, leaving the inhabitants with ten cannon.
Sir Edward also paid owed wages to and accepted the resignation of a group of Colonial Marines - escaped American slaves who had joined the Royal Navy, some of whom had taken part in the burning of Washington DC in 1814 - who remained behind.
Elsewhere, British forces evacuating from positions held in the War of 1812 took many former American slaves with them, to the Caribbean, where a distinct ethnic group in Trinidad - the (a)Merikins - lives on today, and Canada, where a majority of today's Afro-Canadian Nova Scotians are descended from these evacuations.
[The location of "Fort Negro", near the later US army-built Fort Gadsden. It is only in the early 21st century that the significance of Fort Negro is being more widely noted. Historical markers at the site previously referred exclusively to the post as 'British' and didn't mention the ethnicities of the fort's defenders, giving an impression the site was one of Anglo-American conflict, inaccurately casting the site's defenders as "foreigners".]
Sir Edward Nicholls' hoped that the British Government would recognise the group as subjects of the Empire - and therefore at least some of North Florida as a British possession; protecting them from American retaliation.
Unfortunately, the British Government, having agreed a peace treaty with the United States, was wary of any diplomatic foray that may cause further issues with the Americans. A British protectorate of free blacks and native Americans on the very border of some of the most significant US slave states would inevitably lead to conflict, so the agreement was not ratified by the British Government, and the native representative Francis the Prophet (of the Red Stick Creek), was not given an audience with the Prince Regent when he visited London to plead for British protection and recognition.
[Picture: Soldier of the British Corps of Colonial Marines, this formation of escaped American slaves fought bravely in numerous raids, particularly in Virginia, at the British victory at Bladensburg 1814, and took part in the burning of Washington DC.]
The slave-holding United States could not allow this bastion of freedom to exist so close to their border, acting as a magnet for escapees and, at least in the minds of some Georgia plantation owners, a potential staging area for a future invasion of the US by a free black army. There is some evidence of small acts of banditry by groups of free black Americans against isolated American farms and plantations, but it is unclear if these were misidentified Native American actions, deliberate slave-freeing raids, or simply criminal activity exaggerated into a vast threat by American newspapers.
These allegations, and incursions by Americans and American forces into the area being resisted with deadly force by the mixed native American and free black population, providing a pretext for future President Andrew Jackson to begin his conquest of Florida in 1816 by attacking 'Negro Fort'.
["Warriors from Bondage" by Jackson Walker, showing the inhabitants of Fort Negro preparing to fire upon US gunboats. Lack of familiarity with their cannon led to the Fort's fire being ineffective. The 'Redcoat' in the top-right I believe represents Garcon in the remnants of a British uniform, complete with an officer's gorget - the British Empire often awarded these to friendly native chiefs.]
The fort was commanded by "Garcon", a former colonial marine, when communicated with by the US forces on 27 July 1816, who claimed they were in the area legally with permission of the nominal Spanish governor, Garcon replied that he had been given authority by the King of Great Britain to hold the fort, he consequently raised the Union Jack and a Red Flag ("no quarter"). In the ensuring exchange of fire US artillery detonated the fort's powder magazine, with catastrophic results, killing almost everyone inside, including many women and children.
[Picture: In later life, then-President Jackson's execution of two Britons in Florida was used as a political weapon, in this Jackson (left) threatens his foes with "I’ll hang you all up under the 7th section [of the 1806 US Articles of War] as I did Arbuthnot and Ambrister!”, referencing the questionable legality of his actions - which were also used in the 21st century as a precedent for American treatment of "enemy combatants" in Guantanamo Bay.]
Some of the black survivors were re-enslaved by the Americans and shipped north to Georgia's plantations; Garcon was captured alive and executed by a firing squad. At this time the area was still nominally Spanish, so the destruction of Negro Fort marks the only time the United States destroyed a fugitive slave community outside its borders, later elimination of other free black communities, such as Angola (now Bradenton, Manatee county) would take place once Florida had been wholly claimed by the US. The US would go on to fight the Seminole Wars to conquer all of Florida.
Periodically during the American conquest of Florida, envoys of Native American and free black groups would arrived in the Bahamas to plead for British arms, men, and protection. British sympathy with the Floridian resistance was great but never officially recognised, and Andrew Jackson extrajudicially executed two British men, Alexander George Arbuthnot and Robert C. Ambrister (who had been an officer in the majority-black Colonial Marines) in 1818, when they were captured by American forces while fighting alongside the Creek.
Some Afro-Seminole, with possible links to Fort Negro, would eventually resettle as refugees in the Bahamas at Red Bay, Andros Island; a British list of those found at Red Bay in the 1820s included a high proportion of classical names (Achilles, Castor, Hercules, etc), a strong indicator many were former American slaves. ------------------------------------------------------------------------------------------------------------------
A post about the black Colonial Marines, in which I mistakenly say none ever fell back into US hands: