page_title: Platine War
section_title: Allied army advance
hierarchical_section_title: Platine War / Stage 2 – Allied invasion of Argentina / Allied army advance
caption_attribution_description: Español: Batalla del Paso del Tonelero
context_page_description: The Platine War was fought between the Argentine Confederation and an alliance consisting of the Empire of Brazil, Uruguay, and the Argentine provinces of Entre Ríos and Corrientes. The war was part of a long-running dispute between Argentina and Brazil for influence over Uruguay and Paraguay, and hegemony over the Platine region. The conflict took place in Uruguay and northeastern Argentina, and on the Río de la Plata. Uruguay's internal troubles, including the longrunning Uruguayan Civil War, were heavily influential factors leading to the Platine War.
  In 1850, the Platine region was politically unstable. Although the Governor of Buenos Aires, Juan Manuel de Rosas, had gained dictatorial control over other Argentine provinces, his rule was plagued by a series of regional rebellions. Meanwhile, Uruguay struggled with its own civil war, which started after gaining independence from the Brazilian Empire in 1828 in the Cisplatine War. Rosas backed the Uruguayan Blanco party in this conflict, and further desired to extend Argentine borders to areas formerly occupied by the Spanish Viceroyalty of the Río de la Plata. This meant asserting control over Uruguay, Paraguay, and Bolivia.
context_section_description: Shortly after the surrender of Oribe, the Allied forces split into two groups, the plan being for one force to maneuver upriver and sweep down on Buenos Aires from Santa Fe, while the other would make a landing at the port of Buenos Aires itself. The first of these groups, was composed of Uruguayan and Argentine troops, along with the 1st Division of the Brazilian Army under Brigadier General Manuel Marques de Sousa (later the Count of Porto Alegre). It was initially based in the town of Colonia del Sacramento in the south of Uruguay across the Río de la Plata estuary from the city of Buenos Aires.
  On 17 December 1851, a squadron of Brazilian ships, consisting of four steamships, three corvettes and one brig under the command of Grenfell, forced a passage of the Paraná River in the battle which became known as the Passage of the Tonelero. The Argentines had formed a powerful defensive line at The Tonelero Pass, near the cliffs of Acevedo, protected by 16 pieces of artillery and 2,000 riflemen under the command of general Lucio Norberto Mansilla. The Argentine troops exchanged fire with the Brazilian warships but were unable to prevent them from progressing upriver. The following day, the Brazilian ships returned and broke their way through the Tonelero's defences, carrying the remaining troops of Marques de Sousa's Brazilian division upstream towards Gualeguaichu. This second influx of ships caused Mansilla and his soldiers to withdraw in chaos, abandoning their artillery, believing that the Allies were intending to land and attack their positions from the rear.
  The Allied army continued to make its way to the assembly point at Gualeguaichu. Urquiza and his cavalry traveled overland from Montevideo, while the infantry and artillery were carried by Brazilian warships up the Uruguay River. After meeting up, they marched west until they reached the city of Diamante on the east side of the Paraná River in the middle of December 1851. Eugenio Garzón and the Uruguayan troops were taken from Montevideo up to Potrero Perez by Brazilian warships and continued on foot until arriving at Diamante on 30 December 1851, when all the Allied forces were finally reunited.
  From Diamante contingents were ferried to the other side of the Paraná River, landing at Santa Fé. The Confederate Argentine troops in the region ran away without offering any resistance. The Allied Army, or the "Grand Army of South America" as it was officially called by Urquiza, marched on towards Buenos Aires.
  Meanwhile, the second force, comprising the majority of the Brazilian troops (about 12,000 men) under the command of Caxias, had remained in Colonia del Sacramento. The Brazilian commander took the steamship Dom Afonso (named in honor of the late Prince Afonso) and entered the port at Buenos Aires to select the best place to disembark his troops. He expected to have to defeat the Argentine flotilla anchored there, but the force did nothing to stop him and he safely returned to Sacramento to plan his assault. The attack was aborted, however, when news arrived of the Allied victory at Caseros.
caption: Location of the Imperial Armada passing through Tonelero and Argentine batteries.
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