The kingdom of England had its first tentative dealing with West Africa in the reign of Queen Mary I when John Lok returned from a trade voyage to the Guinea coast with 5 Africans in 1555. British seamen were soon attracted by the profitable Portuguese slave trade to the Spanish colonies in America; John Hawkins conducted the first successful British slave trade voyages to Spanish ports across the Atlantic in the 1560s. However, as the Portuguese control of the slave monopoly weakened, the new Dutch Republic began to take over the trade and controlled it from forts built on the Gold Coast of West Africa. Early British trading ventures also began to take advantage of the slaving opportunities later in the seventeenth century. For many years British interest in West Africa was confined to establishing forts from which slaves could be despatched to the trans-Atlantic markets.