Uruguayan Civil War
File:Defensa de montevideo.jpg An illustration of the defense of Montevideo from Isidoro De-Maria's book, Anales de la defensa de Montevideo.
Date 1839–1851 Location Uruguay Result Victory for the Colorados.
Belligerents
Colorados With the support of: France British Empire Kingdom of Sardinia The Empire of Brazil	Blancos With the support of: Argentina
Commanders and leaders
Fructuoso Rivera Samuel Inglefield Giuseppe Garibaldi	Manuel Oribe Juan Manuel de Rosas

The Uruguayan Civil War, also known as "Guerra Grande", was a series of armed conflicts that took place between the Colorados at Montevideo and Blancos at Cerrito in Uruguay from 1839 to 1851. The efforts of the Colorados were supported by France, Great Britain, and Brazil, while the efforts of Blancos were supported by Argentina.

In 1838, Uruguayan president, General Fructuoso Rivera intervened in an internal conflict between the states of the Argentine Confederation. Fructuoso Rivera assumed power in Montevideo in October 1838 after toppling General Manuel Oribe, a pro-Argentine non-interventionist. The French government also had a dispute with the Argentine authorities in Buenos Aires.^[1] French troops first intervened in the war between 1838 and 1842. From 1843 to 1850, both the British and French troops intervened, transforming the conflict into an international war. ^[2] Between 1838 and 1840, French naval squadron was stationed in the River Plate to blockade of port of Buenos Aires.

On December 6, 1842, the Blancos under Manuel Oribe, and the Colorados under Fructuoso Rivera fought the Battle of Arroyo Grande. Rivera's forces were totally defeated, and Oribe proceeded to lay siege to Montevideo.^[3]

With the destruction of the Uruguayan army at the battle of Arroyo Grande, it was assumed that the country's capital, Montevideo, would fall to the combined forces of the Argentinian dictator Juan Manuel Rosas and the former Uruguayan president Manuel Oribe. ^[4] Oribe's siege of Montevideo, Uruguay's capital, lasted for nine years, and Alexandre Dumas described the siege as a "new Troy". ^[2]The newly-freed slaves, who formed a contingent 5,000 strong, and the community of foreign exiles were mostly responsible for the defense of the city. ^[4] The British Empire eventually saved the city by allowing it to receive supplies. First, the British and French naval forces temporarily blockaded the port of Buenos Aires during the December of 1845. Then, the French and British fleets protected Montevideo at sea. French legionnaires, along with Italian legionnaires, led by Giuseppe Garibaldi teamed up with the Colorados in defending the city. Historians believe that the French and British forces intervened in the region to ensure free navigation along the Rio Parana and Rio Uruguay. However, in 1850, both the French and British withdrew after signing a treaty that represented a triumph for Juan Manuel de Rosas of Argentina.^[2]

After the withdrawal of British and French troops, it appeared that Montevideo would fall. However, an uprising against Juan Manuel de Rosas led by Justo José de Urquiza, governor of Argentina's Entre Ríos Province, with the assistance of a small Uruguayan force, changed the situation. Manuel Oribe was defeated in 1851, leaving Colorados in full control of the country. Brazil intervened in Uruguay in the May of 1851, supporting the Colorados with financial and naval forces. In February 1852, Rosas abdicated, and Urquiza's pro-Colorado forces lifted the siege of Montevideo.^[2]

The government of Montevideo rewarded Brazil's financial and military support by signing five treaties in 1851 that provided for perpetual alliance between the two countries. Montevideo confirmed Brazil's right to intervene in Uruguay's internal affairs. Brazil was required to extradite runaway slaves and criminals from Uruguay. During the war, both the Blancos and the Colorados had abolished slavery in Uruguay in order to mobilize the former slaves to reinforce their respective military forces The treaties also allowed joint navigation on the Rio Uruguay and its tributaries, and tax exempted cattle and salted meat exports. The Uruguayan cattle industry was devastated by the war. It also acknowledged Uruguay's debt to Brazil for aid against the Blancos, and Brazil's commitment for granting an additional loan. Uruguay renounced its territorial claims north of the Río Cuareim, thereby reducing its boundaries to about 176,000 kilometers, and recognized Brazil's exclusive right of navigation in the Laguna Merin and the Rio Yaguaron, the natural border between the countries.^[2]

• Battle of Arroyo Grande - December 6, 1842
• Siege of Montevideo - 1843
• Battle of Salto San Antonio - February 1846
• Siege of Montevideo - 1851