In the years between 1524 and 1526, smallpox, introduced from the conquistadors in Panama and preceding the Spanish conquerors in Peru through transmission among natives, had swept through the Inca Empire. Smallpox caused the death of the Inca ruler Huayna Capac as well as most of his family including his heir, caused the fall of the Inca political structure and contributed to the civil war between the brothers Atahualpa and Huáscar. Taking advantage of this, Pizarro carried out a "coup d'état". On 16 November 1532, while the Atahualpa's victorious army was in an unarmed celebration in Cajamarca, the Spanish lured Atahualpa into a trap during the Battle of Cajamarca. The well-armed 168 Spaniards killed thousands of barely armed Inca soldiers and captured the newly minted Inca ruler, causing a great consternation among the natives and conditioning the future course of the fight. When Huáscar was killed, the Spanish tried and convicted Atahualpa of the murder, executing him by strangulation.