Paraná, Entre Ríos
Lagos worked as a clerk and then as a typographist in a state printing press, under the government of Juan Manuel de Rosas. Though nominally federalist, Rosas worked mainly to secure power for himself (and by extension, for Buenos Aires). Lagos, a supporter of the federalist cause, got into trouble and was forced to flee to Paraná, Entre Ríos. Rosas was ousted by a former ally, Justo José de Urquiza, in 1852.