Soon after Sintra's expedition, Portuguese traders started arriving at the harbour. By 1495 they had built a fortified trading post on the coast. The Dutch and French also started arriving and set up trade near the coast. Different European nations started using Sierra Leone as a trading point for slaves brought to the coast by African traders from interior areas undergoing wars and conflicts over territory. In 1562, the English initiated the Triangular Trade when admiral Sir John Hawkins of the Royal Navy transported 300 enslaved Africans – acquired "by the sword and partly by other means" – to the Spanish colony of Santo Domingo on Hispaniola in the Caribbean Sea area of the West Indies islands, where he sold them. Bunce Island, an island on the Sierra Leone River, was used as a base for European slavers as a place for slave ships to dock before sailing via the Middle Passage to the Americas. Until the passage of the Slave Trade Act 1807, the island was operated by the London-based firm Grant, Oswald & Company, who occupied it in 1748.