 Gallo was born in Santiago del Estero and studied at the Monserrat School in Córdoba until he was ordained, graduating as a teacher of art (or philosophy according to other sources) at the University of San Carlos.Gallo was elected to represent Santiago del Estero in the Tucumán Congress and served for the declaration in 1816.He was vice-president of the Congress in August 1816 and twice president after it was moved to Buenos Aires.