[1][2] Born in 1796 in San Luis Province, he studied in a Franciscan monastery when young, and left his studies to join the Regiment of Mounted Grenadiers being summoned by José de San Martín to fight in the War of Independence against Spanish rule.

Lieutenant-general Juan Esteban Pedernera married the former Rosa Juana Heredia in Callao on September 23, 1823; she was born in Perú, in 1805, and died in Buenos Aires, on August 26, 1886.

In the Argentine Civil War, he joined the Unitarian side, under the command of General José María Paz, and fought in La Tablada against federalist forces.

After a long time in exile, he returned to the country after the fall of the Rosas' regime, and acted as Senator for San Luis Province.

In 1856, he was designated commander of the frontier armed forces, and in 1859 he was elected Governor of San Luis, and fought at the Battle of Cepeda that same year.