ORDER OF BATTLE // December 17, 1851
Battle of the Tonelero Pass
Estimated force strength by side, with confidence labels per surviving record.
Forces engaged
1 sides catalogued · combined 2,000 estimated
Argentine Confederation
2,000
Medium-confidence figure
Battle context
The Battle of the Tonelero Pass was an engagement of the Platine War in which Brazilian Imperial Navy warships under John Pascoe Grenfell contested Argentine Confederation forces commanded by Lucio Norberto Mansilla near the cliff of Acevedo on the west bank of the Paraná River. Control of the Paraná passage was a strategic objective in the broader Platine War, as river access shaped the operational reach of both Brazilian and Argentine forces in the region. The engagement reflected Brazil's reliance on naval power to project force along the river systems of the Río de la Plata basin during the conflict.
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