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The War of The Triple Alliance: How Paraguay took on Three Nations and Lost

The War of the Triple Alliance was a conflict that pitted Paraguay against the Triple Alliance of Brazil Argentina and Uruguay. The war has roots in the resolution of the Uruguayan War and lingering territorial claims. The war pitted Paraguay, led by President Franciso Solano Lopez, a nation of 450,000 against the Triple Alliance of Brazil, Argentina, and Uruguay. The war lasted from 1864-1870 and ended disastrously for Paraguay as they lost many territorial claims, up to 69% of its population, and a wrecked economy. It would take decades before Paraguay recovered from the population and economic damages caused by the war. Paraguay essentially became a buffer state between Argentina and Brazil. Paraguay began the war on the offensive but soon shifted to a grueling guerilla campaign that dragged out the war and further damaged the nation.


The main cause of the war stems from the Uruguayan war. The Uruguayan war was a conflict in which the liberal Uruguayan Political Colorado Party, with support from Brazil and Argentina, overthrew the ruling Blanco party, who was allied with Paraguay. The war lasted only six months and resulted in a victory for the Colorado coalition. The war left Paraguay at odds with Brazil and Argentina. Brazil and Argentina would not forget that Paraguay intervened on behalf of a common enemy. Brazillian intervention on behalf of the Colorado party meant that Uruguay and Brazil were on very friendly terms. The three nations all had a score to settle with Paraguay and as a result, they signed the Treaty of the Triple Alliance which united the three nations against Paraguay. Another cause of the war was competition for access to the Paraguay and Parana rivers. The economies of the nations all depended on trading and exporting products. There were very many roads or railroads in this region so the main method of transportation was by boat. The two rivers that gave Paraguay and other nations access to the Atlantic Ocean were the Parana and Paraguay rivers. The nations of the Triple Alliance were thus alarmed when Paraguay began constructing a massive fortress called the Fortress of Humaita. Nicknamed the “Gibraltar of South America” the nations of the Triple Alliance grew concerned that an increasingly hostile and unpredictable Paraguay might choke off access to the vital waterways of the Rio De La Plata Basin. Paraguay also had competing territorial claims with the nations of the Triple Alliance. These causes eventually led to the outbreak of war in December of 1864.

Some of the competing territorial claims that partially caused the War of the Triple Alliance

The War Itself

Despite facing three nations, Paraguay began on the offensive by invading the Braz illian province of Mato Grosso and a few months later the province of Rio Grande do Sul and the Argentine province of Corrientes. Paraguay invaded with two columns and had some success, holding most of the state up through 1868. Paraguay invaded Argentina in hopes of gaining the support of the opposition party there but instead enraged Argentina and caused them to enter into the Triple Alliance and sign the treaty of Triple Alliance. By 1865, Paraguay suffered a key naval defeat on the Parana river which marked the turning point of the war. The allies began an offensive and never looked back. Lopez recognized this and attempted to shock the Allies with a frontal assault at the Battle of Tuyuti. This bloody battle ended with dire losses for Paraguay. The Allied offensive was nearly ended by a disastrous defeat at the Battle of Curupayty in which an overconfident Allied force could not break the Paraguayan trench. This defeat resulted in a change of leadership for the Allies and the suspension of the offensive for 10 months. The Allied campaign set their sights on the monstrous fortress of Humaita and the fortress fell after a lengthy siege. With Humaita out of the way, the Allies marched towards Asuncion, the capital of Paraguay. In a desperate attempt to stave off the Allies, Lopez began filing his armies with children and the elderly. Asuncion was occupied on January 1, 1869. The Allied forces looted the city for several months and a Provincial government was established while a manhunt for Lopez began. Lopez fled his army and began a guerilla campaign with his more devoted followers. This phase of the war known as the Campaign of the hills dragged the war out for another year and caused further damage to the devastated nation of Paraguay. Lopez died at the hands of a Brazillian battalion on March 1, 1870.


The war of the Triple Alliance devastated Paraguay in an almost unfathomable way. While there is no official death count, a method that uses the official Paraguayan census of 1846 and uses the natural growth rate of a population gives us the estimate that Paraguay lost anywhere from 60%-69% of the population. The population loss disproportionately affected men since they made up the army. As a nation, women in Paraguay outnumbered men 4-1 and in the most devastated areas, 20-1. The economy of Paraguay was wrecked as Lopez spent lavishly on war efforts. Paraguay was still paying debts from the war to Brazil until 1943 when the emperor canceled them. Paraguay lost many of its territorial claims to the Triple Alliance and Paraguay in 1870 was about half of its modern size. Paraguay would take many decades to recover and the war halted any modernization efforts. Brazil emerged from the War as the unquestioned most powerful state in South America. Overall, the War of the Triple Alliance should be remembered for the catastrophic damage it caused Paraguay and for being one of the most important events in the history of post-colonial South America.

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