In 1462, Portuguese settlers arrived at Santiago and founded a settlement they called Ribeira Grande (now called Cidade Velha, to avoid being confused with the town of Ribeira Grande on the Santo Antão island). Ribeira Grande was the first permanent European settlement in the tropics. In the 16th century, the archipelago prospered from the Atlantic slave trade. Pirates occasionally attacked the Portuguese settlements. Sir Francis Drake, an English corsair privateering under a letter of marque granted by the English crown, twice sacked the (then) capital Ribeira Grande in 1585 when it was a part of the Iberian Union. After a French attack in 1712, the town declined in importance relative to nearby Praia, which became the capital in 1770.