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.

The Argentine Confederation was the last predecessor state of modern Argentina; its name is still one of the official names of the country according to the Argentine Constitution, Article 35. It was the name of the country from 1831 to 1852, when the provinces were organized as a confederation without a head of state. The governor of Buenos Aires Province managed foreign relations during this time. Under his rule, the Argentine Confederation engaged in conflicts with Brazil, Bolivia, Uruguay, France and the United Kingdom, as well as other Argentine factions during the Argentine Civil Wars.