His father was a minister of the caudillo of San Juan, Nazario Benavídez, Saturnino María Laspiur became a lawyer in 1850 at the National University of Córdoba.

He was sent by the deputies appointed by the revolutionaries, Antonino Aberastain and Domingo Faustino Sarmiento to the 1853 Constituent Congress of Santa Fe.

[citation needed] Laspiur used his newspapers La Tribuna and El nacional to agitate for removal of the "tyrant" Benavídez.

He rejected an offer from the minister and future president Santiago Derqui to regain his freedom in exile in Montevideo, saying he intended to accept having participated in the murder.

From Buenos Aires Laspiur supported the revolution in San Juan that ended with the death of Governor José Antonio Virasoro.

When Aberastain was defeated and killed, he joined the Buenos Aires press campaign against his murderers, forgetting that he had applauded the deaths of Benavidez and Virasoro.

After the Battle of Pavón he was secretary of Colonel Dr. Marcos Paz in his advance inland, which toppled several Federalist governors and replaced them by Unitarians.