Paraguayan War Summary

  • Last updated on November 10, 2022

Also known as the War of the Triple Alliance, or López War, South America’s bloodiest international conflict succeeded in establishing permanent boundaries for Argentina, Brazil, Paraguay, and Uruguay at the cost of overwhelming casualties among the Paraguayans.

Summary of Event

As early as the sixteenth century, Spain and Portugal had vied over access to the Plata estuary, where the Paraná, Paraguay, and Uruguay Rivers empty into the Atlantic Ocean. This impressive river system provided access to the silver-mining regions of Spanish Peru, as well as to the interior of Portuguese Brazil. When the Spanish and Portuguese colonies achieved independence in the first decades of the nineteenth century, the question of which new nation would control the rivers had to be decided. In 1828, Brazil and Argentina Brazil;and Argentina[Argentina] Argentina;and Brazil[Brazil] averted war by creating the independent nation of Uruguay Uruguay;creation of in the contested territory. As a result, Argentina would not totally dominate access to the Plata river system. Paraguayan War (1865-1870) Argentina;and Paraguayan War[Paraguayan War] Brazil;and Paraguayan War[Paraguayan War] López, Francisco Solano Paraguay [kw]Paraguayan War (May 1, 1865-June 20, 1870) [kw]War, Paraguayan (May 1, 1865-June 20, 1870) Paraguayan War (1865-1870) Argentina;and Paraguayan War[Paraguayan War] Brazil;and Paraguayan War[Paraguayan War] López, Francisco Solano Paraguay [g]South America;May 1, 1865-June 20, 1870: Paraguayan War[3830] [g]Argentina;May 1, 1865-June 20, 1870: Paraguayan War[3830] [g]Brazil;May 1, 1865-June 20, 1870: Paraguayan War[3830] [g]Paraguay;May 1, 1865-June 20, 1870: Paraguayan War[3830] [g]Uruguay;May 1, 1865-June 20, 1870: Paraguayan War[3830] [c]Wars, uprisings, and civil unrest;May 1, 1865-June 20, 1870: Paraguayan War[3830] [c]Diplomacy and international relations;May 1, 1865-June 20, 1870: Paraguayan War[3830] [c]Expansion and land acquisition;May 1, 1865-June 20, 1870: Paraguayan War[3830] Mitre, Bartolomé Caxias, duque de Pedro II Flores, Venancio Lynch, Eliza

Meanwhile, the new nation of Paraguay emerged upriver, despite the antagonism of the Argentine dictator Juan Manuel de Rosas. By the end of the 1820’s, the old Spanish viceroyalty of La Plata had been replaced by the countries of Argentina, Paraguay, and Uruguay Uruguay . Independence did not, however, immediately result in stable rule. For decades, Argentina suffered from political conflicts between the region centered around the port of Buenos Aires Buenos Aires and the interior provinces. The Brazilian Empire also experienced political turmoil, as several separatist regional rebellions occurred in 1830 and 1850. Contests for power in Uruguay often resulted in interference from the government of Brazil or Argentina. Paraguay, on the other hand, enjoyed stability under two dictators who promoted self-sufficiency for their people.

In the 1850’s, the issue of boundaries in the region intensified. Brazilian cattle Cattle;in Brazil[Brazil] Brazil;cattle ranching ranchers who had settled along the border of Uruguay ignored official boundaries and allowed their herds to roam freely. As Brazilians prospered along the Uruguayan border, the Paraguayan dictator became concerned that Brazil would become too involved in the affairs of that nation. Paraguayans had come to believe that the political equilibrium of the region depended on preserving the independence of Uruguay. Otherwise, Paraguay’s access to the Paraná and Paraguay Rivers would depend solely on the good will of the Argentines in Buenos Aires.

The years leading up to the war witnessed significant political transitions in Argentina, Brazil, and Paraguay. In 1852, the Argentine dictator was deposed, creating an opportunity for constitutional government. In Brazil, the young emperor Pedro II Pedro II finally succeeded in taming his internal regional conflicts. Still, the country was divided politically between conservatives and the more reform-oriented Liberal Party. Regional differences in the large empire remained pronounced. The Brazilian Brazil;slavery in economy, built upon the export of coffee, sugar, and cotton, depended on the labor of African slaves. The toughest political question of the era had to do with the fate of the institution of slavery, especially after Abraham Lincoln issued the Emancipation Proclamation in the United States in 1863.

In Paraguay, Francisco Solano López, raised to inherit the presidency, came into his birthright upon the death of his father in 1862. In the 1850’s, he had traveled across the Atlantic and witnessed European industrial and military superiority over Russia in the Crimean War. Determined to promote industrialization in Paraguay, he recruited European engineers and technicians to build an iron foundry and a railroad in his country. While in Paris, he met Eliza Lynch Lynch, Eliza , a young Irishwoman, who became his mistress and returned with him to Paraguay. Although they never married, she bore him five children. Presiding over the social scene in Paraguay’s capital city, Asunción, Lynch brought a new level of European sophistication to a nation whose inhabitants were primarily Guarani Indians.

In late 1864, Brazilian troops marched into Uruguay Uruguay to support the presidential bid of Venancio Flores Flores, Venancio , who favored the interests of southern Brazilian ranchers. In protest, Francisco Solano López, now dictator of Paraguay, seized a Brazilian steamer carrying the president of the province of Mato Grosso to his new post. He commandeered the vessel and all that was on it. Shortly thereafter Paraguayan troops crossed into Mato Grosso. Realizing that a military campaign in this remote region of Brazil would not alter the situation in Uruguay, López requested permission from Argentina’s president Bartolomé Mitre Mitre, Bartolomé to send troops through the Argentine province of Corrientes on their way to guarantee the independence of Uruguay. Upon Mitre’s refusal, Paraguay declared war on Argentina and sent in troops that occupied the town of Corrientes. On May 1, 1865, Argentina and Uruguay joined Brazil in the Triple Alliance to fight López.

Young men in Brazil rallied to the cause, joining the army as “Volunteers of the Fatherland.” Paraguay, nonetheless, commanded the largest number of troops, and these soldiers fought tenaciously in what they viewed as a struggle to preserve national autonomy. Brazil and Argentina, however, were far larger countries and could endure more readily a protracted struggle.

For five years, armies of the Triple Alliance attempted to capture López. The climate and terrain in Paraguay were unforgiving. Many soldiers died of disease in the first few months of the war. As the number of casualties rose, enthusiasm for the war waned. Internal conflict in Argentina, exacerbated by the war, meant the Argentines could not spare many soldiers for the Paraguayan campaign. Brazilians, too, began to resist joining the army. To raise troops, Pedro Pedro II agreed to enlist slaves who would be freed once the war ended. Although some Brazilians were concerned about relying on enslaved soldiers, army officers in their command praised their discipline and commitment to the cause of Brazil. Once they returned from the front, these military commanders became strong supporters of freeing all Brazilian slaves.

Brazilians lamented the fact that they were so woefully unprepared for war. A conflict they had believed would be over in months stretched into years. The number of casualties was staggering. Only in 1868 did the forces of the Triple Alliance take Asunción; even then, the war did not end, as López fled with his closest advisers and established a new capital. The duque de Caxias Caxias, duque de , the commander of Brazil’s forces, retired in 1868, exhausted by the prolonged war. He returned to Rio de Janeiro Rio de Janeiro quietly; there was no hero’s welcome for the man who, for thirty years, had fought to preserve the integrity of the empire.

The emperor’s son-in-law next took command of the Brazilian army. For more than a year, they chased López as he moved his forces deeper into the hinterland. By the time López was captured in 1870, his army consisted primarily of teenage boys. Although all sides suffered high casualties in the war, Paraguay was devastated by its defeat. Nonetheless, fears that Paraguayan territory would be divided between Argentina and Brazil were not realized. Paraguay lost some land to those two nations, but it preserved its independence. The war did, however, define national boundaries in the region. It also settled definitively the question of access to the Paraná, Paraguay, and Uruguay Rivers.


The Paraguayan War, or the War of the Triple Alliance, had the greatest impact on the two countries that contributed the most troops to the cause: Paraguay and Brazil. The male population of Paraguay was devastated. The entire population declined by approximately 20 percent over the course of the war, but the number of men who died was far greater than that of women. Possibly as many as 70 percent of Paraguay’s men perished between 1865 and 1870. It would not be easy to return that nation to normalcy. In fact, the political instability generated by the war shattered the fifty years of prosperity that Paraguay had enjoyed immediately after independence.

In Brazil, the end of the war ushered in a series of reforms. In 1871, the Brazilian parliament passed a law freeing all children born to slave women; complete abolition of slavery followed in 1888. During the war, the need for a more professional army had become abundantly clear. In the 1870’s and 1880’s, efforts to modernize recruitment and training of soldiers led to the creation of a much more efficient fighting force. From this newly professionalized group support for republican government grew, and in 1889 the Brazilian emperor was deposed by an army coup d’etat.

Further Reading
  • citation-type="booksimple"

    xlink:type="simple">Barman, Roderick J. Citizen Emperor: Pedro II and the Making of Brazil, 1825-1891. Stanford, Calif.: Stanford University Press, 1999. Includes an excellent chapter on the conduct of the Paraguayan War from the perspective of Brazilian politics.
  • citation-type="booksimple"

    xlink:type="simple">Graham, Richard, ed. A Century of Brazilian History Since 1865: Issues and Problems. New York: Alfred A. Knopf, 1969. Includes three selections on the war, one each from the Brazilian, Paraguayan, and Argentine perspectives.
  • citation-type="booksimple"

    xlink:type="simple">Kraay, Hendrick, and Thomas L. Whigham, eds. I Die With My Country: Perspectives on the Paraguayan War, 1864-1870. Lincoln: University of Nebraska Press, 2004. A carefully chosen collection of ten essays written by North American and South American scholars that portray the complexities of the war.
  • citation-type="booksimple"

    xlink:type="simple">Leuchars, Chris. To the Bitter End: Paraguay and the War of the Triple Alliance. Westport, Conn.: Greenwood Press, 2002. A detailed, engagingly written account of the military campaigns of the Paraguayan War.
  • citation-type="booksimple"

    xlink:type="simple">Whigham, Thomas L. The Paraguayan War: Causes and Early Conduct. Lincoln: University of Nebraska Press, 2002. The first of a proposed multivolume study; provides a comprehensive account of the background to the war, as well as the first years of conflict. Meticulously researched in all four of the countries involved.

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Categories: History