Paraguayan War Begins
The Paraguayan War, fought from 1864 to 1870, pitted Paraguay against the Triple Alliance of Brazil, Argentina and Uruguay. It was the deadliest and most destructive conflict in the history of South America. Paraguay suffered catastrophic losses, and the war reshaped the balance of power in the River Plate region, leaving lasting scars on national memory in all the countries involved.
The roots of the war lay in the unsettled politics of the River Plate basin. Paraguay was a landlocked country that depended on the river system for trade, and it had developed under a series of strong, centralizing rulers. Since 1862 it had been led by Francisco Solano López, who commanded one of the largest armies in the region. Brazil and Argentina, meanwhile, both sought influence over Uruguay, where rival factions, the Blancos and the Colorados, were locked in a struggle. Paraguay saw Brazilian intervention in Uruguay as a threat to the regional balance, and López cast himself as its defender.
The war began in late 1864, when Paraguay seized a Brazilian ship and invaded the Brazilian province of Mato Grosso. In 1865 López demanded passage for his troops across Argentine territory in Corrientes, and when Argentina refused, Paraguay invaded there too. In response, Brazil, Argentina and a Colorado-led Uruguay signed the Treaty of the Triple Alliance in May 1865. Paraguay's offensive soon stalled, and the Brazilian navy's victory at Riachuelo in 1865 gave the Allies control of the rivers. Allied forces then pushed into Paraguay, where the fortress of Humaitá held out for a long time before falling in 1868. Asunción was occupied in early 1869, but López kept fighting a guerrilla-style campaign until he was killed by Brazilian troops in March 1870.
The human cost was enormous. Paraguay lost a very large share of its population to combat, disease, hunger and displacement, and the male population was especially hard hit. Estimates vary widely, from roughly one-tenth to well over half of the people, and historians still debate the exact figure. Brazil, Argentina and Uruguay also suffered heavy casualties, mostly from disease.
After the war, Paraguay lost territory to Argentina and Brazil and was occupied by Brazilian troops for several years. Its economy and society were deeply disrupted. The conflict strengthened the Brazilian army as a political force, a factor often linked to the later fall of the Brazilian monarchy in 1889. Memory of the war remains contested. In Paraguay, López has at times been celebrated as a national hero, while others blame his ambition for the disaster.