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How did Juan Manuel de Rosas lose power in 1851?

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Panoramic aerial view of Buenos Aires, Argentina, featuring the Obelisk monument, wide avenues lined with trees, and dense city buildings under a blue sky. — Buenos Aires Aerial view of the city center, including the obelisk (center), Buenos Aires.

In 1851, the Argentine dictator Juan Manuel de Rosas faced a critical turning point that led to his eventual loss of power. That year, Justo José de Urquiza, the governor of the province of Entre Ríos, formed a powerful alliance with Brazil and Uruguay to challenge Rosas’s long-standing rule.1

This coalition successfully forced Rosas’s troops to abandon their long-running siege of Montevideo. The conflict culminated on February 3, 1852, at the Battle of Caseros, where Urquiza’s forces defeated the main army of Rosas. Following this decisive military defeat and the abandonment of his remaining political supporters and troops, Rosas was forced to flee to England, effectively ending his 17-year dictatorship.12