After the earthquake of 1773 life changed dramatically in the City of Santiago de Guatemala, which would shortly move to the site of present-day Guatemala City by order of King Charles III of Spain. After 1775 the city would be known as Antigua Guatemala. Castellanos remained loyal to the Archbishop, Pedro Cortés y Larraz, and only left with his musicians, the clergy, and the religious orders when they were forced to do so, arriving at the new site in November 1779. Despite the hardship of his new life, Castellanos kept up his work, composing four or five works every year. Among his pupils, several became able composers, such as Manuel Silvestre Pellegeros and Pedro Nolasco Estrada Aristondo, his eventual successor as "maestro de capilla."