Bunce Island was first settled and fortified by English slave traders in c. 1670.
During its early history, the castle was operated by two London-based firms: the Royal African Company and its offshoot, the Gambia Adventurers, the latter a "Crown-chartered company" or parastatal subsidised by the English government.
On October 31, 1678, at Gresham College the later offered the former the contents of their investment on the island for 4,644l.
4s.
9d.
The castle was not commercially successful but it served as a symbol of English influence in the region, where Portuguese slave traders had been established since the 1500s.

The early phase of the castle's history ended in 1728 when Bunce Island was raided by José Lopez da Moura, a Luso-African slave trader based in the area.
He was the richest man in present-day territory of Sierra Leone, the grandson of a Mane king and part of the hybrid Luso-African community that had developed along the lower rivers.
This  class acted as middlemen, resisting efforts by the Royal African Company to monopolise trade with African rulers.
Lopez led others in destroying the Bunce Island factory.

Bunce Island was abandoned until the mid-1740s.
It was later operated by the London-based firm Grant, Oswald & Company, who took over in 1748.
In 1785 Bunce and a number of other dependent islands were conveyed to the company of John and Alexander Anderson.
Throughout the late 18th century, it was a highly profitable enterprise.
During the second half of the 18th century, the companies sent thousands of African captives from Bunce Island to sales for plantations on the British- and French-controlled islands in the West Indies, and to Britain's North American colonies.
The London-based owners grew wealthy from the castle's operations.

Bance Island House, the headquarters building where the Chief Agent lived with his senior officers, was at the centre of the castle.
Immediately behind it was the open-air slave yard, which was divided between a large area for men and a smaller one for women and children.
Remnants of two watchtowers, a fortification with places for eight cannons, and a gunpowder magazine remain standing.
Some of the cannons bear the royal cypher of King George III.
At the south end of the island, several inscribed tombstones mark the graves of slave traders, slave ship captains, and the foreman of African workers.

The slave traders who did business at Bunce Island came from a variety of backgrounds.
During the castle's early history, Afro-Portuguese—part of what historian Ira Berlin described as the "Atlantic Creole generation"—sold slaves and local products there.
They were well-established along the rivers near the coast and were descendants of male Portuguese slave traders known as lançados and African women, and were often bilingual.
During the island's later history, Afro-English dynasties became established in communities along the West African coast, beginning in the 17th century.
By 1800, there were about 12,000 Afro-English in this area.
 Mixed-race men from such families as the Caulkers, Tuckers and Clevelands sold slaves and traded goods at Bunce Island.
Like the Portuguese descendants, they occupied a middle ground, often marrying into the upper classes of African tribes.
The slave ships came from  London, Liverpool and Bristol; from Newport, Rhode Island in the North American colonies; and from France and Denmark.
They transported slaves mostly to British markets in the Caribbean and the American South.

Bunce Island was an important British commercial outpost and an attractive target during times of war.
French naval forces attacked the castle four times (1695, 1704, 1779, and 1794), damaging or destroying it each time.
The attack of 1779 took place during the American Revolutionary War when the rebel Continental Army's French allies took advantage of the conflict to attack British assets outside North America.
Pirates, including Bartholomew Roberts or "Black Bart", the most notorious pirate of the 18th century, attacked in 1719 and 1720.
The British traders rebuilt the castle
Bunce Island was first settled and fortified by English slave traders in c. 1670. During its early history, the castle was operated by two London-based firms: the Royal African Company and its offshoot, the Gambia Adventurers, the latter a "Crown-chartered company" or parastatal subsidised by the English government. On October 31, 1678, at Gresham College the later offered the former the contents of their investment on the island for 4,644l. 4s. 9d. The castle was not commercially successful but it served as a symbol of English influence in the region, where Portuguese slave traders had been established since the 1500s.
The early phase of the castle's history ended in 1728 when Bunce Island was raided by José Lopez da Moura, a Luso-African slave trader based in the area. He was the richest man in present-day territory of Sierra Leone, the grandson of a Mane king and part of the hybrid Luso-African community that had developed along the lower rivers. This  class acted as middlemen, resisting efforts by the Royal African Company to monopolise trade with African rulers. Lopez led others in destroying the Bunce Island factory.
Bunce Island was abandoned until the mid-1740s. It was later operated by the London-based firm Grant, Oswald & Company, who took over in 1748. In 1785 Bunce and a number of other dependent islands were conveyed to the company of John and Alexander Anderson. Throughout the late 18th century, it was a highly profitable enterprise. During the second half of the 18th century, the companies sent thousands of African captives from Bunce Island to sales for plantations on the British- and French-controlled islands in the West Indies, and to Britain's North American colonies. The London-based owners grew wealthy from the castle's operations.
Bance Island House, the headquarters building where the Chief Agent lived with his senior officers, was at the centre of the castle. Immediately behind it was the open-air slave yard, which was divided between a large area for men and a smaller one for women and children. Remnants of two watchtowers, a fortification with places for eight cannons, and a gunpowder magazine remain standing. Some of the cannons bear the royal cypher of King George III. At the south end of the island, several inscribed tombstones mark the graves of slave traders, slave ship captains, and the foreman of African workers.
The slave traders who did business at Bunce Island came from a variety of backgrounds. During the castle's early history, Afro-Portuguese—part of what historian Ira Berlin described as the "Atlantic Creole generation"—sold slaves and local products there. They were well-established along the rivers near the coast and were descendants of male Portuguese slave traders known as lançados and African women, and were often bilingual. During the island's later history, Afro-English dynasties became established in communities along the West African coast, beginning in the 17th century. By 1800, there were about 12,000 Afro-English in this area.  Mixed-race men from such families as the Caulkers, Tuckers and Clevelands sold slaves and traded goods at Bunce Island. Like the Portuguese descendants, they occupied a middle ground, often marrying into the upper classes of African tribes. The slave ships came from  London, Liverpool and Bristol; from Newport, Rhode Island in the North American colonies; and from France and Denmark. They transported slaves mostly to British markets in the Caribbean and the American South.
Bunce Island was an important British commercial outpost and an attractive target during times of war. French naval forces attacked the castle four times (1695, 1704, 1779, and 1794), damaging or destroying it each time. The attack of 1779 took place during the American Revolutionary War when the rebel Continental Army's French allies took advantage of the conflict to attack British assets outside North America. Pirates, including Bartholomew Roberts or "Black Bart", the most notorious pirate of the 18th century, attacked in 1719 and 1720. The British traders rebuilt the castle
Bunce Island