In Asia and the Americas, the war had gone well for the Dutch. Those parts of the war were mainly fought by proxies, especially the Dutch West and East India companies. These companies, under charter from the Republic, possessed quasi-sovereign powers, including the power to make war and conclude treaties on behalf of the Republic. After the invasion of Portuguese Brazil by a WIC amphibious force in 1630, the extent of New Holland, as the colony was called, grew gradually, especially under its governor-general Johan Maurits of Nassau-Siegen, in the period 1637–1644. It stretched from the Amazon river to Fort Maurits on the São Francisco River. Soon a large number of sugar plantations flourished in this area, enabling the company to dominate the European sugar trade. The colony was the base for conquests of Portuguese possessions in Africa also (due to the peculiarities of the trade winds that make it convenient to sail to Africa from Brazil in the Southern Hemisphere). Beginning in 1637 with the conquest of Portuguese Elmina Castle, the WIC gained control of the Gulf of Guinea area on the African coast, and with it of the hub of the slave trade to the Americas. In 1641, a WIC expedition sent from Brazil under command of Cornelis Jol conquered Portuguese Angola. The Spanish island of Curaçao (with important salt production) was conquered in 1634, followed by a number of other Caribbean islands.