Captain Diego de Holguín participated in the conquest of Guatemala, Izalco, Cuzcatlan and under the command of Pedro de Alvarado. He was alderman of the municipality of Santiago de los Caballeros de Guatemala. Along with Gonzalo de Alvarado, was one of the founders of the first settlement of San Salvador, next to a fortress Cuzcatlecos, and became its first mayor in April 1525.