Spain-Inca War mod for Empire Earth

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. In less than a century, the Inca had expanded their empire from about 400,000 km² (150,000 sq mi) in 1448 to 1,800,000 km² (690,000 sq mi) in 1528, just before the arrival of the Spanish. This vast area of land varied greatly in cultures and in climate. Because of the diverse cultures and geography, the Inca allowed many areas of the empire to be governed under the control of local leaders, who were watched and monitored by Inca officials. Under the administrative mechanisms established by the Inca, all parts of the empire answered to, and were ultimately under the direct control of, the Emperor. Scholars estimate that the population of the Inca Empire was more than 16,000,000.

Some scholars, such as Jared Diamond, believe that while the Spanish conquest was undoubtedly the proximate cause of the collapse of the Inca Empire, it may very well have been past its peak and already in the process of decline. In 1528, Emperor Huayna Capac ruled the Inca Empire. He could trace his lineage back to a "stranger king" named Manco Cápac, the mythical founder of the Inca clan^1, who according to tradition emerged from a cave in a region called Paqariq Tampu.

Huayna Capac was the son of the previous ruler, Túpac Inca, and the grandson of Pachacuti, the Emperor who, by conquest, had commenced the dramatic expansion of the Inca Empire from its cultural and traditional base in the area around Cusco. On his accession to the throne, Huayna Capac had continued the policy of expansion by conquest, taking Inca armies north into what is today Ecuador. While he had to put down a number of rebellions during his reign, by the time of his death, his legitimacy was as unquestioned as was the primacy of Inca power.

Expansion had caused its own set of problems. Many parts of the empire retained distinct cultures, which were at best reluctant to become part of the imperial project. Due to its size, and the fact that all communication and travel had to take place by foot or by boat, the Inca Empire proved increasingly difficult to administer.

Huayna Capac relied on his sons to support his reign. While he had many legitimate and illegitimate children (legitimate meaning born of his sister-wife, under the Inca system), two sons are historically important. Prince Túpac Cusi Hualpa, also known as Huáscar, was the son of Coya Mama Rahua Occllo of the royal line. The second was Atahualpa, an illegitimate son who was likely born of a daughter of the last independent King of Quitu, one of the states conquered by Huayna Capac during the expansion of the Inca Empire.These two sons would play pivotal roles in the final years of the Inca Empire.

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.

At the time of Huayna Capac's death, Huáscar was in the capital Cuzco, while Atahualpa was in Quito with the main body of the Inca army. Huáscar had himself proclaimed Sapa Inca (i.e. "Only Emperor") in Cuzco, but the army declared loyalty to Atahualpa. The resulting dispute led to the Inca Civil War.