Paraguayan War (1864-1870): The War of the Triple Alliance

The Paraguayan War, also known as the War of the Triple Alliance, was fought from December 1864 to 1 March 1870 between Paraguay and the allied powers of Brazil, Argentina and Uruguay. Begun by Paraguay’s president Francisco Solano López, it became the bloodiest interstate war in the history of Latin America. Paraguay was invaded, occupied and lost a large share of its population, a disaster that still shapes the country’s memory.

Background

Landlocked Paraguay depended on the Paraná and Paraguay rivers for access to the Atlantic. Since independence it had been ruled by strong leaders: José Gaspar Rodríguez de Francia, then Carlos Antonio López, who opened the country to trade and built a railway, an arsenal and a large army. When Carlos Antonio died in 1862, his son Francisco Solano López became president.

Paraguay had long-running border disputes with both of its large neighbours: the Empire of Brazil under Emperor Pedro II, which had become independent after Brazilian independence in 1822, and Argentina, where Bartolomé Mitre had recently unified the country under Buenos Aires.

Small Uruguay lay between the two giants. In 1864 a civil war there pitted the ruling Blanco party against the Colorados of Venancio Flores, who had Brazilian and Argentine sympathy. López regarded the Blancos as allies and warned Brazil not to intervene. In October 1864 Brazilian troops entered Uruguay anyway.

Outbreak

López responded quickly. On 12 November 1864 Paraguay seized the Brazilian steamer Marquês de Olinda on the Paraguay River, and in December Paraguayan forces invaded the Brazilian province of Mato Grosso. When Argentina refused to let Paraguayan troops cross its territory to reach Brazil’s southern province of Rio Grande do Sul, Paraguay declared war on Argentina in March 1865 and occupied the city of Corrientes in April.

Meanwhile Flores had taken power in Uruguay with Brazilian help. On 1 May 1865 Brazil, Argentina and Uruguay signed the Treaty of the Triple Alliance, pledging to fight until López was removed. A secret clause outlined territorial gains for Brazil and Argentina.

Course of the war

Paraguay’s offensive soon failed. On 11 June 1865 the Brazilian navy destroyed much of Paraguay’s river fleet at the Battle of Riachuelo. A Paraguayan column that invaded Rio Grande do Sul was surrounded and surrendered at Uruguaiana in September 1865, and Paraguay withdrew from Corrientes.

In April 1866 the allies invaded southern Paraguay. On 24 May 1866 López launched a massive surprise attack on their camp at Tuyutí, the largest pitched battle in South American history; it failed with very heavy Paraguayan losses. But on 22 September 1866 the allies suffered their own disaster when a frontal assault on the trenches at Curupayty was shattered.

The war then bogged down around the great river fortress of Humaitá. Cholera and other diseases killed thousands on both sides. Command passed to Brazil’s Marquis (later Duke) of Caxias, who reorganised the allied army; Brazil carried most of the burden from then on. Humaitá was abandoned by its garrison in July 1868 after a long siege.

In December 1868 a series of battles near the Pikysyry stream, including Itororó, Avay and Lomas Valentinas, destroyed most of López’s remaining army. Allied troops entered the capital, Asunción, in early January 1869.

López refused to surrender and retreated into the interior, raising new forces that included old men and boys. At Acosta Ñu on 16 August 1869 many child soldiers died fighting Brazilian troops; the date is now Paraguay’s Children’s Day. Hunted by Brazilian forces under the Count of Eu, López was killed at Cerro Corá on 1 March 1870.

A nation at war

Paraguay entered the war with one of the largest standing armies in South America, but it had a much smaller population and economy than its enemies. As losses mounted, López mobilised almost every able man and later boys and old men as well. Women grew food, worked in the army’s supply system and, in 1867, donated jewellery to the war effort. Wartime newspapers, some printed in Guaraní, the language most Paraguayans spoke, celebrated the soldiers and mocked the enemy.

The war also turned inward. In 1868, convinced that a conspiracy was forming against him, López ordered mass arrests at San Fernando. Hundreds of people were tortured or executed, including his own brother Benigno, his foreign minister and many senior officers and foreigners.

The allies faced their own strains. Brazil raised units of “Volunteers of the Fatherland” but increasingly relied on conscription and on enslaved men who were freed in exchange for service. In Argentina the war was unpopular in several provinces, and uprisings in the interior in 1866–1867 forced Mitre to withdraw troops from the front. The Brazilian army even used observation balloons to study Paraguayan positions around Humaitá in 1867, one of the first military uses of balloons in South America.

Key people

• Francisco Solano López – president of Paraguay, seen by some as a national hero and by others as a ruthless ruler who led his country to ruin.
• Pedro II – Emperor of Brazil, who insisted on fighting until López was removed.
• Bartolomé Mitre – president of Argentina and first commander-in-chief of the allied armies.
• Duke of Caxias – Brazil’s leading general, who commanded the allies from 1867 to early 1869.
• Venancio Flores – Colorado leader who became Uruguay’s ruler with Brazilian support.
• Eliza Lynch – López’s Irish-born companion, who was with him at Cerro Corá.

The human cost

The death toll is one of the most debated questions of the war. Paraguay’s pre-war population is uncertain, with estimates ranging from roughly 300,000 to over 450,000. Many scholars estimate that Paraguay lost between 60 and 70 percent of its people, with the adult male population devastated; a minority of historians argue for much lower losses.

Most deaths, on all sides, came from disease, hunger and exposure rather than combat.

Consequences

Brazilian troops occupied Paraguay until 1876. Under peace treaties Paraguay gave up territory north of the Apa River to Brazil and the Misiones region and part of the Chaco to Argentina. In 1878 an arbitration by US President Rutherford B. Hayes awarded Paraguay the disputed central Chaco; the town of Villa Hayes is named after him. Paraguay faced decades of poverty, debt and political instability.

The war also changed its victors. In Brazil it strengthened the army and its officers’ political ambitions, and many enslaved men had been freed to serve. Both developments fed the debates that led to the abolition of slavery in Brazil in 1888 and the fall of the monarchy in 1889. In Argentina, the war helped consolidate the national state.

Myths and facts

A once-popular theory held that Britain provoked the war to open Paraguay to British trade. Most modern historians reject this view: the conflict grew mainly out of regional rivalries, and British involvement was limited to loans and trade with the allies.

It is often said that only women and children survived in Paraguay. The male population was indeed devastated, and women played a central role in rebuilding, but the most extreme figures are not supported by recent research.

Timeline

• 1864, October: Brazil intervenes in the Uruguayan civil war.
• 1864, 12 November: Paraguay seizes the Brazilian ship Marquês de Olinda.
• 1864, December: Paraguay invades Mato Grosso.
• 1865, 1 May: Treaty of the Triple Alliance signed.
• 1865, 11 June: Brazilian naval victory at Riachuelo.
• 1866, 24 May: Battle of Tuyutí.
• 1866, 22 September: Allied defeat at Curupayty.
• 1868, July–August: Fall of Humaitá.
• 1869, January: Allied troops occupy Asunción.
• 1870, 1 March: López is killed at Cerro Corá; the war ends.

Why it matters

The Paraguayan War reshaped South America’s borders and politics and remains a defining national trauma for Paraguay. It is a stark example of how a regional dispute can escalate into a war of near-annihilation.