The Uruguayan Civil War was a civil war in Uruguay that was fought between the liberal Colorados and the conservative Blancos from 1839 to 1851; however, armed conflict between the two parties started in 1832 and did not end until the final military defeat of the Blancos in 1904.
After the proclamation of Uruguayan independence in 1828, conflict over primacy broke out between the leader of the Thirty-Three Orientals Juan Antonio Lavalleja and the general Fructuoso Rivera. The country became divided between Rivera's Colorados and Lavalleja's Blancos. The Colorados who were favored by the urban middle classes, merchants, professionals, intellectuals, and liberal thinkers advocating for modernization and centralization of government; they were predominantly strong in Montevideo, where economic and political power was concentrated. Coastal regions, which were more urbanized and connected to international trade, tended to support the Colorados. The Blancos were largely supported by rural landowners, particularly in the interior of the country. Many agricultural workers and laborers in rural areas also sided with the Blancos, as they often aligned with the interests of the landowners. The Blancos had a conservative base, appealing to traditionalists who favored a more agrarian and less centralized government. The Blancos were strongest in the interior provinces, such as Durazno, Tacuarembó, and Paysandú. These areas had a strong agrarian economy and a population that identified with the rural elite.
Montevideo strongly supported the Colorados, Canelones leaned towards the Colorados, Maldonado had some support for the Colorados, Lavalleja leaned towards the Colorados in urban areas, and Rocha primarily supported the Colorados. San Jose, Soriano, Rio Negro, and Tacuarembo strongly supported the Blancos; Colonia and Florida predominantly favored the Blancos, Paysandú and Treinta y Tres generally supported the Blancos, Flores primarily leaned towards the Blancos, Cerro Largo supported the Blancos, and Salto leaned towards the Blancos. In Artigas, there was some support for both parties, but leaned towards the Blancos. Rivera was mixed, with factions of both parties present.
Rivera was chosen as Uruguay's first president on 6 November 1830, but Lavalleja's supporters attempted to kill him in June 1832. On 3 July, the Montevideo garrison revolted and called for Lavalleja to be made commander-in-chief. Rivera, with the help of Argentine Unitarios, defeated Lavalleja on 18 September 1832 at the Battle of Tupambae, forcing Lavalleja to flee to the Brazilian province of Rio Grande do Sul. There, he organized a new force with the support of Buenos Aires strongman Juan Manuel de Rosas and mounted a failed invasion of Uruguay in March 1834. In March 1835, the Blanco Manuel Oribe was elected President of Uruguay, while Rivera remained as commander of the army. Oribe removed Rivera from command in January 1836 and gave amnesty to Lavalleja. On 16 July 1836, Rivera rebelled against Oribe, who ordered his men to wear a white (blanco) armband to show their loyalty. Rivera ordered his supporters to wear red (colorado) armbands, setting the stage for war.
Lavalleja organized an army in Argentina to support Oribe, who battled Rivera and Argentine Unitarians led by General Juan Lavalle. On 19 September 1836, Rivera was defeated at the Battle of Carpinteria, where his troops joined the newly proclaimed Riograndense Republic. Rivera invaded Uruguay in 1837 and defeated Oribe at the Battle of Yucutuja on 22 October 1837 before completely crushing him at the Battle of Palmar on 15 June 1838. That same year, France blockaded Buenos Aires in support of the Peru-Bolivian Confederation, and France allied with the Colorados to defeat Rosas' ally Oribe. On 24 October 1838, Oribe was forced to flee to Buenos Aires, enabling Rivera to return to power.
After Rosas refused to recognize Rivera and made plans to restore Oribe to power, Rivera and Lavalle prepared troops to attack Buenos Aires. On 6 December 1842, Rivera's forces were utterly defeated at the Battle of Arroyo Grande, and Oribe laid siege to Montevideo. The Great Siege of Montevideo lasted for nine years, and 5,000 newly freed slaves and foreign exiles defended the city. Joaquin Suarez's Gobierno de la Defensa claimed to rule Uruguay from Montevideo, while Oribe's Gobierno del Cerrito took its name from its headquarters in Montevideo's Cerrito de la Victoria neighborhood. The British Empire's Royal Navy and the French Navy blockaded Buenos Aires and protected Montevideo from the city, and French, Spanish, and Italian legionnaires led by Giuseppe Garibaldi joined the Colorados in defending Montevideo. In 1846, the 73rd (Perthshire) Regiment of Foot was dispatched by Britain to help defend Montevideo from the Argentines. In 1850, however, the French and British withdrew. Only Justo Jose de Urquiza's rebellion against Rosas back in Argentina prevented the city from falling, and Oribe was defeated in 1851, leaving the Colorados in full control of the country. Brazil intervened in Uruguay in May 1851, supporting the Colorados with financial and naval forces. The Platine War resulted in Rosas' overthrow in February 1852 and Urquiza's rescue of Montevideo.
Uruguay proceeded to sign a treaty of perpetual alliance with Brazil in 1851. The war devastated Uruguay's cattle industry, and Uruguay was forced to renounce its territorial claims north of the Rio Cuareim to repay Brazil for its aid. The early 1860s saw the civil war flare up in the Uruguayan War, which resulted in the Colorados' seizure of power from 1865 to 1959. In 1870, the Colorados and Blancos called a truce; the Colorados were allowed to control Montevideo and the coastal region, while the Blancos would rule the hinterland with its agricultural estates. Political feuding continued with the Revolution of the Lances in 1870-1872 and ultimately with Aparicio Saravia's failed 1904 uprising, the last action of the civil war.