García Banqueda was born in Santiago, the son of Antonio García, Lieutenant in the "Dragones de la Reina" ("Queen's Dragoons") and of Juana Banqueda. In 1817 (at the age of 12), he became a cadet in the recently formed Military Academy, created by Bernardo O'Higgins that year. He fought in the Battle of Maipú, during the Chilean War of Independence. He also participated in the Valdivia and Chiloé campaigns of 1825 and 1826. He married Dolores Carmona Fonseca, and they had several children.