He now wished to make conquest of the countries to the south, which the natives declared to be a great and wealthy empire, but having too few men to attempt the enterprise, he returned to Darien, carrying with him a treasure valued at nearly half a million of dollars--the largest treasure yet collected in America. He sent messengers to Spain, but before these arrived Don Pedrarias Davila had been sent out to supersede him in command. The King, however, in consideration of his services, sent letters appointing Balboa _Adelantado_ or Admiral. The enormous project of conveying ship-building material across the Isthmus was accomplished, and two brigantines were constructed. Adverse weather and other misfortunes prevented the Spaniards from reaching Peru, and Pedrarias recalled Balboa to Darien. Balboa obeyed, never dreaming of the treachery awaiting him. He was seized and imprisoned, and finally condemned to death by the jealous Pedrarias, and the sentence was carried out in spite of the protests of the colonists. The conquest of Peru was afterward accomplished by Pizarro, who, while he was as able a man as Balboa, was much more cruel and unscrupulous. Three years later Magellan entered the South Sea, after sailing around the southern extremity of the continent. It was Magellan who gave this ocean the name Pacific, in recognition of the fine weather he encountered in crossing it. His fleet reached the islands of the Indian Archipelago, and returned to Europe by way of the Cape of Good Hope, thus completing the first circumnavigation of the globe. In the same year which witnessed the unjust execution of Balboa (1517), the northern coast of Yucatan was explored, and also the southern coast of Mexico. Instead of encountering naked savages, the explorers were surprised to find well-clad and highly civilized people, so bold and warlike as to drive off the intruders with great slaughter. Velasquez, governor of Cuba, determined to conquer the wealthy country thus discovered, and prepared a fleet of ten vessels, which he sent out under command of Hernando Cortes, a man who had already achieved some military distinction. He landed in Mexico on March 4th, 1519, where his ships and artillery, and especially his horses, created the wildest fear and astonishment among the natives, who regarded the strangers as divine beings. They were soon to be undeceived, however, for a reign of war and oppression was begun, which resulted in the death of the Emperor Montezuma, the levelling of their ancient temples, and the ultimate extinction of the Aztec nation. Meanwhile, the mainland of the American continent had been visited and partly explored.