Aguirre, Lope de (c. 1518-61), Spanish adventurer.
Aguirre participated in the civil wars among the Spanish conquerors of Peru after he arrived there in 1544.
In 1560, Aguirre took part in a sailing expedition down the Amazon River in search of the legendary kingdom of El Dorado. The most important find of the expedition was the discovery that the Orinoco River connected to the Amazon.
During this voyage, Aguirre rebelled against the leader of the expedition, Pedro de Ursua. Upon reaching the headwaters of the Amazon River, he took part in the murder of de Ursua. Aguirre then renounced his allegiance to King Philip II of Spain and convinced the other men to do likewise. He later took command of the expedition, putting to death anyone who opposed his plans. He intended to establish an independent kingdom upon his return to Peru.
