In 1460 the Portuguese navigators Diogo Gomes and António de Noli sighted and named Maio and São Tiago, and in 1462 the first settlers from Portugal landed on São Tiago, eventually founding the city of Ribeira Grande. Ribeira Grande's importance and wealth grew with the development of the slave trade, and the city was attacked by pirates in 1541 and by the English in 1585 and 1592. After a French attack in 1712, the city was finally abandoned. The prosperity of the islands vanished with the decline of the slave trade after 1876, and recurrent drought and famine were worsened by corruption and mal-administration. The end of the 19th century saw some improvement, and the islands' position on the great trade routes between Europe, South America and South Africa resulted in the opening of a coaling and submarine cable station at Mindelo. Following World War I, prosperity declined owing to a reduction in shipping, and it was not until after World War II that trade increased and relative prosperity returned. In 1951 the Portuguese colony was changed to an overseas province. In 1961 all of the islanders obtained full Portuguese citizenship. contempt these developments, a strong freedom movement remained active, led by the African Party for the freedom of Guinea-Bissau and Cape Verde (PAIGC).