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Battle of the Riachuelo, 1865: the river battle that turned the Paraguayan War

War of the Triple Alliance · 11 June 1865 · Brazil vs Paraguay · ~5 min read · Updated October 2026

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Painting of a black steam frigate flying Brazilian flags amid smoke on a river below red cliffs, with wrecked ships and men struggling in the water.

Eduardo de Martino (1838 to 1912), Combate Naval do Riachuelo, via Wikimedia Commons, public domain.

At a glance

Empire of Brazil (Triple Alliance)Admiral Francisco Manoel Barroso (frigate Amazonas)
vs
ParaguayAdmiral Pedro Ignacio Meza; Marshal-President Francisco Solano López (overall)
Date
11 June 1865
Location
Paraná River near the mouth of the Riachuelo, just south of Corrientes, Argentina
War
War of the Triple Alliance (Paraguayan War), 1864 to 1870
Ships
Brazilian squadron of nine steamers with about 2,300 sailors and soldiers against eight Paraguayan steamers and six towed gun barges, with guns and infantry on the bank (Bento, Navigator); Thomas Whigham counts eleven Allied and nine Paraguayan steamers
Losses
Paraguay four steamers and at least two gun barges, Meza mortally wounded; Brazil two steamers, Belmonte and Jequitinhonha, and 245 men out of action by its own reports
Outcome
Brazilian victory; Paraguay lost control of the river and turned to the defensive
Quick answer

What was the Battle of the Riachuelo?

The Battle of the Riachuelo, on 11 June 1865, was the decisive naval battle of the War of the Triple Alliance. A Paraguayan flotilla under Pedro Ignacio Meza attacked the Brazilian squadron of Francisco Manoel Barroso on the Paraná River near Corrientes, Argentina. After a fight that lasted most of the day, the Paraguayans retreated upriver with four steamers lost and Meza mortally wounded. The victory gave the Allies control of the river, ended Paraguay's hopes of advancing south and sealed it off from the outside world.1

It was a battle of wooden steamers fought in a narrow, twisting channel between sandbanks, under the fire of guns hidden on the cliffs. Brazil remembers it as the greatest day of its navy; Paraguay's British engineer George Thompson, who watched the survivors come home, thought the Paraguayans had fought with great bravery against immeasurably superior ships.2

Background: a war decided on the rivers

In the War of the Triple Alliance of 1864 to 1870, Paraguay's marshal-president, Francisco Solano López, fought the Empire of Brazil, Argentina and Uruguay. In 1865 his armies invaded the Brazilian province of Rio Grande do Sul and the Argentine province of Corrientes, and that campaign hung on the Paraná River.3

The war had begun over Uruguay. Brazil intervened there in 1864, and in November López answered by seizing the Brazilian mail steamer Marquês de Olinda on the Paraguay River and then invading the Brazilian province of Mato Grosso. In May 1865 Argentina, Brazil and Uruguay allied against him. The Marquês de Olinda, now armed, would sail in Paraguay's flotilla at the Riachuelo.4

Dark locator map of the south of South America with its river systems, a gold star in a glowing circle where the Paraguay River joins the Paraná, and a small world map inset
The battle was fought on the Paraná just below Corrientes, a little downstream of the point where the Paraguay River joins it: the river highway between Paraguay and the sea. Drawn for this article from Natural Earth data, with no modern borders. Location map: © Echoes of Battle (data: Natural Earth, public domain)

As long as Brazilian warships held the river, the Paraguayan army in Corrientes had an enemy squadron at its back. The Allied attack on the city of Corrientes on 25 May 1865 made that plain, and López set out to destroy the Brazilian squadron that lay at anchor below the city.5 › Battle of Vuelta de Obligado, 1845

Both sides had also been racing to buy the new armored ships. Brazil started with a large navy and kept modernizing it; Paraguay, Fernando Ribas De Martini shows in the Brazilian navy's journal Navigator, tried to close the gap by ordering ironclads in Europe. None had arrived when the two fleets met, so the Riachuelo was fought between unarmored ships.6

Armies and commanders

Barroso commanded nine steamers: the frigate Amazonas, his flagship, with the Parnaíba, Iguatemi, Araguari, Mearim, Jequitinhonha, Beberibe, Belmonte and Ipiranga. They carried, by the count in Navigator, 2,287 men, 1,113 sailors and 1,174 soldiers of the army, who fought from the decks as marines. Barroso's own letter of 9 May, published by Pedro Henrique de Souza Ribeiro in 2025, speaks of about 2,650 men to feed.7

Meza led eight steamers, among them the Tacuarí, Paraguarí, Ygurey, Salto Oriental and the captured Brazilian Marquês de Olinda, with six chatas in tow: flat gun barges that floated almost awash, each carrying one heavy gun, a target very hard to hit. A ninth steamer, the Rio Blanco, ran aground on the way down. Behind them, on the cliffs at the mouth of the Riachuelo, Colonel José María Bruguez had placed field batteries and infantry.8

On paper the Paraguayans had firepower to match. Navigator counts 41 guns on Meza's steamers, six more on the chatas and 22 in Bruguez's batteries, with some 2,000 riflemen on the cliffs. But the guns on the Brazilian steamers were heavier, Whigham notes, and Thompson, who knew the Paraguayan ships well, called them immeasurably inferior in ships and guns.9

The battle in phases

The plan. Meza was to come down the river at midnight, leave his chatas under the cliffs, then turn and fall on the anchored Brazilians at dawn, board them and capture them; if surprise failed, he was to fight his way back downstream under the guns on the bank.10

Surprise lost. The plan went wrong from the start. The time spent trying to free the grounded Rio Blanco meant that the Paraguayans arrived in daylight. A correspondent of the Jornal do Commercio aboard the Belmonte wrote that the lookouts cried out at about 8:30 in the morning; Thomas Whigham puts the Paraguayan arrival at 11. Either way, the surprise was gone.11

The cliffs. The Paraguayan steamers ran past the Brazilian line, and the Brazilians followed them down into the narrow channel by the Riachuelo, under the fire of the batteries on the cliffs, the chatas and riflemen on the banks and islands. Several Brazilian ships ran aground: the Jequitinhonha stuck fast under the guns, and the Belmonte, holed below the waterline, had to be run ashore to keep from sinking.12

The Parnaíba. The hardest fighting came when three Paraguayan steamers closed on the Parnaíba. Paraguayan boarders swept her deck from the stern to the mainmast and hauled down her flag before the Amazonas and other ships came up and drove them off with grapeshot. Among the Brazilians killed defending the flag was Midshipman João Guilherme Greenhalgh; the sailor Marcílio Dias, mortally wounded in the same fight, is remembered with him.13

Nineteenth-century wood engraving of several steamships locked together on a river, their masts and rigging tangled, with men fighting on the decks and others in the water
The Parnaíba holding off three Paraguayan steamers, an engraving by Antoine Léon Morel-Fatio after a sketch sent from the river, published in Paris in Le Monde illustré two months after the battle. Antoine Léon Morel-Fatio after a sketch by M. Muller, Le Paranahyba soutient le choc de trois vapeurs paraguayens, wood engraving, Le Monde illustré no. 436, 19 August 1865. Public domain, via Wikimedia Commons

Turning point: Barroso's attack

For a time the battle hung in the balance, with the Parnaíba fighting three steamers and two more Brazilian ships aground. Then Barroso took the Amazonas in a wide arc against Meza's ships one after another, using his larger, heavier flagship to run them down. One Paraguayan steamer sank at once; others were rammed onto the banks or disabled, and the battle turned in Brazil's favor.14

Lithograph of a large paddle steamer flying a commander's pennant ramming a smaller steamer in rough water, the smaller ship heeling over with men in the water around her
The frigate Amazonas, flying Barroso's pennant, running down a Paraguayan steamer: a drawing published in 1865 by Antônio Luís von Hoonholtz, who commanded the gunboat Araguari in the battle. Antônio Luís von Hoonholtz, A Fragata Amazonas com o pavilhão do Chefe Barroso mettendo a pique um vapor, lithograph, Semana Illustrada no. 249, 1865. Public domain, via Wikimedia Commons

Meza was mortally wounded. At nightfall the four Paraguayan steamers still afloat withdrew upriver, all badly damaged, and the Brazilians, with damaged ships of their own and several still aground, did not press the pursuit in the dark.15

Thompson saw why the boarding attacks on which López had counted had failed. In his judgment the Brazilian ships stood so much higher out of the water than the Paraguayan ones that the boarders could hardly reach their decks, they had boarding nets rigged, and their screw steamers slipped away easily from attackers who carried no grappling irons.16

Aftermath

Paraguay lost four steamers, the Jejuí, the Marquês de Olinda, the Salto Oriental and the Paraguarí. Of the six chatas, two were sunk; Navigator says the other four were taken, Thompson that they took refuge in the Riachuelo. Brazil lost the Jequitinhonha, abandoned on her sandbank, and the Belmonte. How many men died is disputed. By the Brazilian officers' reports, as Navigator gives them, 245 Brazilians were put out of action, 87 of them killed, and Brazilian estimates put Paraguayan losses at no fewer than 1,500; Thompson, on the Paraguayan side, counted about 300 Brazilian and 200 Paraguayan casualties.17

Lithograph of a young naval officer in a dark uniform falling back with a pistol in his hand beside a flag on a ship's deck, while men with a boarding pike and sabers crowd in behind him and another man lies on the deck
The death of Midshipman João Guilherme Greenhalgh, killed defending the flag when the Paraguayans boarded the Parnaíba, as Henrique Fleiuss drew it for the Rio de Janeiro weekly Semana Illustrada in 1865. Henrique Fleiuss, Morte do Guarda-marinha Greenhalgh na Batalha do Riachuelo, lithograph, Semana Illustrada no. 251, 1865. Public domain, via Wikimedia Commons

In the days that followed the Brazilians burned the Paraguayan wrecks they could not use, the Paraguarí on 14 June and the Marquês de Olinda on 17 June.18

Meza died of his wounds. Within weeks López decided to pull his forces back into Paraguay, and by the end of October his army in Corrientes was crossing the Paraná home; for the rest of the war he fought on the defensive. In 1866 Barroso was made Baron of Amazonas, a title named after his flagship.19

Legacy and memory

The Riachuelo closed the river. The Allied blockade of Paraguay that followed cut it off from the arms it had ordered abroad, including the ironclads being built for it in Europe, which ended up under the Brazilian flag. Paraguay's surviving steamers never again challenged the Allied squadron in open battle, and the war that the Riachuelo turned would last until 1870.20

In Brazil the battle became a founding legend. The navy keeps 11 June as its great anniversary, and Barroso, Greenhalgh and Marcílio Dias are still held up to its officers as models of courage. Not everyone shared the admiration for Barroso: Thompson, who saw the battle from the other side, thought he should have been court-martialed for letting the Paraguayan steamers escape. Ribeiro, reading Barroso's letter, cautions against seeing the victory as inevitable: a month before the battle his worries were sandbanks, shallows and food.21

The battle also lives on in paint: Victor Meirelles's great canvas of the Riachuelo, painted for the Brazilian state, hangs in the National Museum of Fine Arts in Rio de Janeiro.22

Notes

A number in the text points to a note; each note names the works that paragraph draws on, listed in full under Sources.

  1. Thomas L. Whigham, “Riachuelo, Battle of the”; André Cezar Siqueira, “Batalha Naval do Riachuelo: 150 anos de uma vitoriosa Operação Conjunta da Marinha e do Exército do Brasil”; Vera Blinn Reber, “War of the Triple Alliance”. ↩
  2. André Cezar Siqueira, “Batalha Naval do Riachuelo: 150 anos de uma vitoriosa Operação Conjunta da Marinha e do Exército do Brasil”; Thompson, The War in Paraguay; Cláudio Moreira Bento, “O 159º aniversário da Batalha Naval do Riachuelo de 11 junho 1865, a maior batalha naval da América do Sul, e a participação de contingentes do Exército”. ↩
  3. Vera Blinn Reber, “War of the Triple Alliance”; Thomas L. Whigham, “Riachuelo, Battle of the”; Armada Argentina, “Guerra de la Triple Alianza (1864-1870)”. ↩
  4. Vera Blinn Reber, “War of the Triple Alliance”; Thompson, The War in Paraguay; Cláudio Moreira Bento, “O 159º aniversário da Batalha Naval do Riachuelo de 11 junho 1865, a maior batalha naval da América do Sul, e a participação de contingentes do Exército”. ↩
  5. Thomas L. Whigham, “Riachuelo, Battle of the”; André Cezar Siqueira, “Batalha Naval do Riachuelo: 150 anos de uma vitoriosa Operação Conjunta da Marinha e do Exército do Brasil”; Cláudio Moreira Bento, “O 159º aniversário da Batalha Naval do Riachuelo de 11 junho 1865, a maior batalha naval da América do Sul, e a participação de contingentes do Exército”. ↩
  6. Fernando Ribas De Martini, “A corrida pela tecnologia para controlar o Prata, na rota de Riachuelo”; Cláudio Moreira Bento, “O 159º aniversário da Batalha Naval do Riachuelo de 11 junho 1865, a maior batalha naval da América do Sul, e a participação de contingentes do Exército”. ↩
  7. Cláudio Moreira Bento, “O 159º aniversário da Batalha Naval do Riachuelo de 11 junho 1865, a maior batalha naval da América do Sul, e a participação de contingentes do Exército”; André Cezar Siqueira, “Batalha Naval do Riachuelo: 150 anos de uma vitoriosa Operação Conjunta da Marinha e do Exército do Brasil”; Pedro Henrique de Souza Ribeiro, “"Your friend and brother Barroso": uma nova carta do Barão do Amazonas”. ↩
  8. André Cezar Siqueira, “Batalha Naval do Riachuelo: 150 anos de uma vitoriosa Operação Conjunta da Marinha e do Exército do Brasil”; Cláudio Moreira Bento, “O 159º aniversário da Batalha Naval do Riachuelo de 11 junho 1865, a maior batalha naval da América do Sul, e a participação de contingentes do Exército”; Thompson, The War in Paraguay; Thomas L. Whigham, “Riachuelo, Battle of the”. ↩
  9. André Cezar Siqueira, “Batalha Naval do Riachuelo: 150 anos de uma vitoriosa Operação Conjunta da Marinha e do Exército do Brasil”; Thomas L. Whigham, “Riachuelo, Battle of the”; Thompson, The War in Paraguay. ↩
  10. André Cezar Siqueira, “Batalha Naval do Riachuelo: 150 anos de uma vitoriosa Operação Conjunta da Marinha e do Exército do Brasil”; Thomas L. Whigham, “Riachuelo, Battle of the”; Armada Argentina, “Guerra de la Triple Alianza (1864-1870)”. ↩
  11. Cláudio Moreira Bento, “O 159º aniversário da Batalha Naval do Riachuelo de 11 junho 1865, a maior batalha naval da América do Sul, e a participação de contingentes do Exército”; André Cezar Siqueira, “Batalha Naval do Riachuelo: 150 anos de uma vitoriosa Operação Conjunta da Marinha e do Exército do Brasil”; Thomas L. Whigham, “Riachuelo, Battle of the”. ↩
  12. André Cezar Siqueira, “Batalha Naval do Riachuelo: 150 anos de uma vitoriosa Operação Conjunta da Marinha e do Exército do Brasil”; Thompson, The War in Paraguay; Thomas L. Whigham, “Riachuelo, Battle of the”. ↩
  13. Thompson, The War in Paraguay; André Cezar Siqueira, “Batalha Naval do Riachuelo: 150 anos de uma vitoriosa Operação Conjunta da Marinha e do Exército do Brasil”; Cláudio Moreira Bento, “O 159º aniversário da Batalha Naval do Riachuelo de 11 junho 1865, a maior batalha naval da América do Sul, e a participação de contingentes do Exército”; Revista do Clube Naval, “Editorial”. ↩
  14. André Cezar Siqueira, “Batalha Naval do Riachuelo: 150 anos de uma vitoriosa Operação Conjunta da Marinha e do Exército do Brasil”; Thomas L. Whigham, “Riachuelo, Battle of the”; Thompson, The War in Paraguay. ↩
  15. Thompson, The War in Paraguay; André Cezar Siqueira, “Batalha Naval do Riachuelo: 150 anos de uma vitoriosa Operação Conjunta da Marinha e do Exército do Brasil”; Thomas L. Whigham, “Riachuelo, Battle of the”. ↩
  16. Thompson, The War in Paraguay. ↩
  17. André Cezar Siqueira, “Batalha Naval do Riachuelo: 150 anos de uma vitoriosa Operação Conjunta da Marinha e do Exército do Brasil”; Thompson, The War in Paraguay; Thomas L. Whigham, “Riachuelo, Battle of the”. ↩
  18. André Cezar Siqueira, “Batalha Naval do Riachuelo: 150 anos de uma vitoriosa Operação Conjunta da Marinha e do Exército do Brasil”; Cláudio Moreira Bento, “O 159º aniversário da Batalha Naval do Riachuelo de 11 junho 1865, a maior batalha naval da América do Sul, e a participação de contingentes do Exército”; Thompson, The War in Paraguay. ↩
  19. Thompson, The War in Paraguay; Thomas L. Whigham, “Riachuelo, Battle of the”; Vera Blinn Reber, “War of the Triple Alliance”; Cláudio Moreira Bento, “O 159º aniversário da Batalha Naval do Riachuelo de 11 junho 1865, a maior batalha naval da América do Sul, e a participação de contingentes do Exército”. ↩
  20. Fernando Ribas De Martini, “A corrida pela tecnologia para controlar o Prata, na rota de Riachuelo”; Cláudio Moreira Bento, “O 159º aniversário da Batalha Naval do Riachuelo de 11 junho 1865, a maior batalha naval da América do Sul, e a participação de contingentes do Exército”; Vera Blinn Reber, “War of the Triple Alliance”; Armada Argentina, “Guerra de la Triple Alianza (1864-1870)”. ↩
  21. Revista do Clube Naval, “Editorial”; Cláudio Moreira Bento, “O 159º aniversário da Batalha Naval do Riachuelo de 11 junho 1865, a maior batalha naval da América do Sul, e a participação de contingentes do Exército”; Thompson, The War in Paraguay; Pedro Henrique de Souza Ribeiro, “"Your friend and brother Barroso": uma nova carta do Barão do Amazonas”. ↩
  22. Armada Argentina, “Guerra de la Triple Alianza (1864-1870)”; Cláudio Moreira Bento, “O 159º aniversário da Batalha Naval do Riachuelo de 11 junho 1865, a maior batalha naval da América do Sul, e a participação de contingentes do Exército”. ↩

Sources

Frequently asked questions

When was the Battle of the Riachuelo?

On Sunday 11 June 1865, on the Paraná River near the mouth of the Riachuelo, just south of Corrientes in Argentina.

Who fought at the Riachuelo?

The Brazilian squadron of Francisco Manoel Barroso, nine steamers carrying sailors and army troops, against a Paraguayan flotilla of eight steamers and six gun barges under Pedro Ignacio Meza, backed by guns and infantry on the riverbank.

Who won the Battle of the Riachuelo?

Brazil. The Paraguayans lost four steamers and retreated upriver; Brazil lost two ships but kept control of the Paraná.

How many men died at the Riachuelo?

The figures differ. Brazilian reports give 245 Brazilians out of action, 87 of them killed, and estimate Paraguayan losses at 1,500 or more; George Thompson, who served with the Paraguayan army, counted about 300 Brazilian and 200 Paraguayan casualties.

What were the chatas?

Flat-bottomed gun barges that the Paraguayans towed into battle. Each carried one heavy gun and floated almost level with the water, which made them very hard to hit.

Why was the Riachuelo so important?

It gave the Allies control of the rivers, ended Paraguay's offensive into Argentina and Brazil and allowed a blockade that kept Paraguay from receiving the arms and ironclads it had ordered abroad.

How is the Riachuelo remembered in Brazil?

The Brazilian navy celebrates 11 June as its great anniversary, and Admiral Barroso, Midshipman Greenhalgh and the sailor Marcílio Dias are honored as its heroes.

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