The Spanish conquest of the Inca Empire, also known as the Conquest of Peru, was one of the most important campaigns in the Spanish colonization of the Americas. After years of preliminary exploration and military skirmishes, 168 Spanish soldiers under conquistador Francisco Pizarro, his brothers, and their indigenous allies captured the Sapa Inca Atahualpa in the 1532 Battle of Cajamarca. It was the first step in a long campaign that took decades of fighting but ended in Spanish victory in 1572 and colonization of the region as the Viceroyalty of Peru. The conquest of the Inca Empire, led to spin-off campaigns into present-day Chile and Colombia, as well as expeditions towards the Amazon Basin.

When the Spanish arrived at the borders of the Inca Empire in 1528, it spanned a considerable area and was by far the largest of the four grand pre-Columbian civilizations. Extending southward from the Ancomayo, which is now known as the Patía River, in southern present-day Colombia to the Maule River in what would later be known as Chile, and eastward from the Pacific Ocean to the edge of the Amazonian jungles, it covered some of the most mountainous terrains on Earth.

The Spanish conquistador Pizarro and his men were greatly aided in their enterprise by invading when the Inca Empire was in the midst of a war of succession between the princes Huáscar and Atahualpa. Atahualpa seems to have spent more time with Huayna Capac during the years when he was in the north with the army conquering Ecuador. Atahualpa was thus closer to and had better relations with the army and its leading generals. When both Huayna Capac and his eldest son and designated heir, Ninan Cuyochic, died suddenly in 1528 from what was probably smallpox, a disease introduced by the Spanish into the Americas, the question of who would succeed as emperor was thrown open. Huayna had died before he could nominate the new heir.