Colorados ("Reds"). The Colorados were led by Fructuoso Rivera and represented the business interests of Montevideo; the Blancos were headed by Manuel Oribe, who looked after the agricultural interests of the countryside and promoted protectionism. Defeat of Oribe In order to support Oribe, Lavalleja organized an army in Argentina and moved against Rivera, who was helped by Argentine Unitarians led by General Juan Lavalle. On September 19, 1836, Rivera was defeated at the Battle of Carpintería and fled to Brazil, where his troops joined the newly proclaimed Riograndense Republic. With the help of this republic Rivera invaded Uruguay in 1837 and on October 22 defeated Oribe's forces at the Battle of Yucutujá and completely crushed Oribe on June 15, 1838 Battle of Palmar. In 1838 France had started a naval blockade of Buenos Aires port in support of their allies the Peru–Bolivian Confederation who were involved in the War of the Confederation with the Argentine Confederation and Chile. Unable to deploy land troops, France looked for allied forces to fight Buenos Aires strongman Juan Manuel de Rosas on their behalf. For this purpose they supported Fructuoso Rivera and helped him to defeat Oribe, who was on good terms with Rosas. On October 24, 1838, Oribe resigned and fled to Buenos Aires, and Rivera assumed power. Return of Oribe Rosas did not recognize Rivera as a legitimate President, and sought to restore Oribe to power. Rivera and Juan Lavalle prepared troops to attack Buenos Aires. At this point, both the British and French troops intervened, transforming the conflict into an international war. 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 utterly defeated, and Oribe laid siege to Montevideo. Great Siege of Montevideo 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 Buenos Aires governor Juan Manuel de Rosas and the former Uruguayan president Manuel Oribe. However, Oribe's siege of Montevideo lasted for nine years. 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. By 1843 Montevideo's population of thirty thousand inhabitants was highly cosmopolitan with Uruguayans making up only a third of it. The remaining were chiefly Italian (4205),