Cortes, Pizarro, Orellana, and Cabeza de Vaca waged wars against the natives of the South American Continent, namely the Aztecs and the Incas. The Spanish were very small in number when the famous conquistador - Francisco Pizarro conquered the city of Cuso, which was also capital of the Incan Civilization. In this legendary conquest, the Inca King Atahualpa, who was held hostage by Francisco Pizarro, filled the room in which he was being held hostage, with gold as a ransom.