Battle of the Tonelero Pass

The Battle of the Tonelero Pass, also known as Passage of the Tonelero, was a battle fought near the cliff of Acevedo, in the west bank of the Paraná River, Argentina, on 17 December 1851, between the Argentine Confederation Army commanded by Lucio Norberto Mansilla and warships of the Brazilian Imperial Navy led by John Pascoe Grenfell.

The battle
In 17 December 1851, the Brazilian fleet commanded by Grenfell was near the cliff of Acevedo in the river Paraná, with the intention to break through the Argentine defenses of Tonelero pass. There were eight Brazilian warships: four steam corvettes, Dom Pedro, Dom Pedro II, Dom Pedro and Recife, that towed two sailing corvettes, Dona Francisca and União, plus a brig, Calíope. On board Grenfell's flagship, Dom Afonso, were Brigadier General Marques de Sousa and the Argentines Colonel Wenceslao Paunero, Lieutenant-Colonel Bartolomé Mitre and Lieutenant-Colonel Domingo Faustino Sarmiento. The ships ferried half of the troops that composed the 1st Division of Imperial Infantry. The rest of the division was waiting at Colonia del Sacramento, Uruguay.

To oppose the passage, there were 16 cannons and 2,000 soldiers commanded by Lucio Norberto Mansilla, son-in-law of the leader of the Argentine Confederation, Juan Manuel de Rosas. For one hour the Argentines fired more than 450 cannon rounds in the direction of the Brazilian ships, causing little damage, but killing four sailors and wounding other five. The warships counterattacked, without causing major damage to the Argentine forces, killing eight soldiers and wounding twenty. The squadron landed the troops at Diamante, Entre Ríos and part of the ships returned to bring the other battalions that stayed behind in Colonia. Mansilla believed that the Brazilian division was going to land right on his main position. He fled along with his men, leaving all the artillery and other equipment behind.