When the Spanish conquistador Francisco Pizarro arrived in South America in 1532, the Inca empire hung at stake in civil war between two half-brothers, Atahualpa and Huascar, sons of the last Inca emperor. This war of royal succession was waged with the same military means that had won the Inca empire, and that had been gradually developed over centuries in the Andes: armies of hundreds of thousands of foot soldiers with trains of pack llamas and auxiliaries on a vast scale, led by a nobility trained from boyhood in the arts of war, and supported by a monumental infrastructure of roads, storehouses, and forts, and a taxation bureaucracy that ballooned as the empire grew.