In this letter, missionary Junípero Serra informs the viceroy of New Spain, Antonio María de Bucareli, of the destruction of Mission San Diego. Since the sixteenth century, Catholic settlements called missions were essential elements in Spain’s colonization of the North American borderlands. Spanish missionaries approached the Indigenous populations through a friendly exchange that involved gifts. The missions acted benevolently as a counterweight against the ambitions of the conquistadors, who conscripted Native Americans as a labor source. Less benevolently, the missionaries worked with the support of the crown to expand its dominions. Missions had military support, usually from presidios (military fortifications) built in the same location. The conversion of the Indigenous populations to Christianity usually meant the loss of their own beliefs and languages. Moreover, the missionary system was not exempt from physical abuse. Those actions led to several revolts across different missions in the American Southwest. In California, the missionary effort began during the second half of the eighteenth century. Junípero Serra, a priest of the Franciscan order, played an important role in this project. On July 16, 1769, he founded Mission San Diego, which would be destroyed by the Native population six years later.