 His best military performance was during the war of 1839, defending the government of José Ignacio de Márquez against the revolt of General José María Obando, due to the administration’s closure of the Catholic convents in the city of Pasto.This victory propelled him to the political arena and he was nominated as presidential candidate by President Márquez.Herrán also served as Envoy Extraordinary and Minister Plenipotentiary to the United States, Ecuador, the Holy See, and Costa Rica.