A rancher and soldier, educated and with a firm character, Segura brought order to the province after the pointless cruelties that Aldao had inflicted.

He asked for assistance from Juan Manuel de Rosas, governor of Buenos Aires province and effective ruler of the Argentina Confederation.

For that reason, Dr. Bernardo de Irigoyen, Argentina's ambassador to Chile, who was residing in Mendoza, organized a coup by which Segura was deposed on 4 April 1847 and replaced by an obscure local commander, Alejo Mallea.

When news of the Battle of Caseros (3 February 1852) reached Mendoza, the legislature decided that Mallea was too closely identified with the defeated Rosas, so they deposed him.

He helped to restore General Nazario Benavídez as governor of the neighboring government of San Juan after he had been deposed in a coup.

Segura authorized use of Chilean copper coins, established a new state printing shop and swore to observe the Constitution of Argentina of 1853.

Segura moved to Paraná, Entre Ríos, the capital of the Argentina Confederacy, where he gave military and diplomatic service to presidents Justo José de Urquiza and Santiago Derqui.