Political map of North America & the Caribbean 22 May 1520 (Captivity of Moctezuma II): Soon after arriving in Tenochtitlan, Cortés (Hernán Cortés) seized Moctezuma (Moctezuma II) and, through him, became indirect ruler of the Aztec Empire. This situation lasted some months until April 1520, when an expedition arrived from Cuba with orders to arrest Cortés (Pánfilo de Narváez) (its arrival would also unintentionally lead to millions of indigenous deaths by introducing smallpox to Mexico (Cocoliztli epidemics)). Cortés raced to the coast and dealt with this new challenge, but during his absence the acting Spanish governor massacred large numbers of Aztecs while they were celebrating a religious festival (Massacre in the Great Temple of Tenochtitlan), destroying Aztec–Spanish relations.