It originally comprised rebellious territories of the former Spanish Viceroyalty of the Río de la Plata dependencies and had Buenos Aires as its capital.

In the midst of the war of independence, during the entire 1810–1831 period there were serious conflicts among ever-changing factions regarding the organization of the state and the political aims of the revolutionary governments.

These conflicts involved coups d'état, mutinies, politically motivated trials, banishments and imprisonments and finally developed into an outright civil war.

While some advocated a strong and executive central government with little accountability to the regional interests, a position at first favored by the "enlightened" revolutionary and independentist elements, others sought to integrate representatives from the provinces in a larger deliberative assembly.

However, as it became evident that such an arrangement was not effective enough to lead the war efforts, a triumvirate assumed executive powers while the assembly retained some controlling functions.

The government of the United Provinces of South America felt threatened by the growing appeal of the Liga Federal, so they did nothing to repel the incoming Portuguese invasion of Misiones Orientales and the Banda Oriental, the stronghold of Artigas.

Brazilian General Carlos Frederico Lecor, thanks to their numerical and material superiority, defeated Artigas and his army and occupied Montevideo on 20 January 1817, but the struggle continued for three long years in the countryside.

Following a long civil war, the following provinces joined to become the Argentine Republic: Buenos Aires (The outpost of Carmen de Patagones in Patagonia is now part of Buenos Aires Province), Catamarca, Córdoba, Corrientes, Entre Ríos, Jujuy, La Rioja, Mendoza, Salta, San Juan, San Luis, Santa Fe, Santiago del Estero, and Tucumán.