He studied law at the Universidad Mayor Real y Pontificia San Francisco Xavier de Chuquisaca, but soon changed to a career of arms. He began his military career at the Battle of Ingavi in 1841 and later studied at the French Military Academy of Saint Cyr while serving as secretary of the Bolivian legation in France. As part of his military training, he participated in the Algerian campaign under the command of the Duke of Aumale, an event that would be recorded in his memoirs. Like many other members of the elite of his time, he entered into Freemasonry, allowing him to befriend the most prominent figures in the political world of the region. Upon his return to Bolivia, he entered political life as a supporter of José María de Achá, but when he Melgarejo ousted him, Campero was exiled to Chile and Argentina. Later, he would become a trusted man of the caudillo Mariano Melgarejo.
