The Dutch first began to ply Saint Martin's ponds for salt in the 1620s. Despite the Dutch presence on the island, the Spaniards recaptured it in 1633. One year later, they built a fort (now Fort Amsterdam, near Philipsburg) and another artillery battery at Pointe Blanche to assert their claim and control access to Great Bay salt pond. A massive influx of African slaves took place in the 18th century with the development of sugarcane plantations by the French and Dutch.