The settlement of Spanish America began with Columbus's second voyage. He had discovered the two largest islands of the Antilles, Cuba and Hispaniola. Alexander VI was himself a Spaniard, already under heavy obligations to the Catholic monarchs and looking to them for support in his endeavour to create a principality in Italy for his son. The little island of Cubagua became the site of the Spanish settlement of New Cadiz, founded to exploit the pearl fishery. More permanent, and more significant for the future, were the settlements in Central America, on the isthmus coast which Columbus had found on his fourth voyage and where the Columbus family later held their only mainland possession, the little duchy of Veragua. The conquest of Mexico is the best known and best documented of all the Spanish campaigns in the New World. Alvarado, Olid, Sandoval, in imitation of Cortes, added great semi-independent provinces to the kingdom of New Spain.