Uruguay Independent

The territory east of the Uruguay River, known as the Banda Oriental, was long contested between Spanish and Portuguese America. After Brazil annexed the region as its Cisplatine Province, Uruguayan patriots led by Juan Antonio Lavalleja, the famous 'Thirty-Three Orientals,' rose in revolt in 1825, and the United Provinces of the Rio de la Plata (Argentina) backed their cause, igniting war with the Brazilian Empire.

The Cisplatine War of 1825 to 1828 proved costly and indecisive for both Brazil and Argentina. With British diplomatic mediation, the two powers signed a peace treaty, the Convention of 1828, agreeing to relinquish their claims and recognize the Banda Oriental as a sovereign buffer state rather than allow either to absorb it.

Uruguay thus emerged as an independent republic, with its first constitution adopted in 1830. Its creation reflected British interest in keeping the strategic Rio de la Plata estuary out of the exclusive control of any single neighbor. The new nation's early decades were nonetheless turbulent, marked by civil conflict between the Colorado and Blanco factions and continued interference from its larger neighbors.