Juan Manuel José Domingo Ortiz de Rosas, nicknamed "Restorer of the Laws", was an Argentine politician and army officer who ruled Buenos Aires Province and briefly the Argentine Confederation. Although born into a wealthy family, Rosas independently amassed a personal fortune, acquiring large tracts of land in the process. Rosas enlisted his workers in a private militia, as was common for rural proprietors, and took part in the disputes that led to numerous civil wars in his country. Victorious in warfare, personally influential, and with vast landholdings and a loyal private army, Rosas became a caudillo, as provincial warlords in the region were known. He eventually reached the rank of brigadier general, the highest in the Argentine Army, and became the undisputed leader of the Federalist Party.

The War of the Confederation was a military confrontation waged by the United Restoration Army, the alliance of the land and naval forces of Chile and the Restoration Army of Peru, formed in 1836 by Peruvian soldiers opposed to the confederation, and the Argentine Confederation against the Peru–Bolivian Confederation between 1836 and 1839. As a result of the Salaverry-Santa Cruz War, the Peru-Bolivia Confederation was created by General Andrés de Santa Cruz, which caused a power struggle in southern South America, with Chile and the Argentine Confederation, as both distrusted this new and powerful political entity, seeing their geopolitical interests threatened. After some incidents, Chile and the Argentine Confederation declared war on the Peru-Bolivian Confederation, although both waged war separately.