In about 1419 Prince Henry the Navigator incorporated the uninhabited Madeiras into Portugal's overseas territories. To three of his captains he delegated the task of settlement: Zarco and Teixeira in Madeira, Perestrelo in Porto Santo. Funchal's founder, Joâo Gonçalves Zarco, is prominently memorialized in the city. To make Madeira cultivable, forests were burned and mountainside terraces ( poios ) were constructed. Despite harsh terrain, massive soil erosion, and difficult access to water, agriculture remains Madeira's lifeblood. In the late sixteenth century, wine replaced sugar as the Island's chief export commodity. Madeira was a nexus of Atlantic trade in the days of sailing ships, and a frequent target for pirate raids. Spain ruled the Madeiras, Azores, and mainland Portugal from 1580 to 1640. In 1660 the British, already influential in island viniculture, signed a commercial treaty with Portugal, and between 1807 and 1814 they occupied Madeira. Their shipping interests opened the island to nineteenthand twentieth-century British tourism. In the 1950s seaplanes linked Madeira to Portugal and England. Porto Santo's international terminal, a NATO emergency base, opened in 1960; Madeira's opened in 1965. Portugal granted limited local autonomy to the Madeiras in 1940 and regional autonomy in 1976.