Excerpts from Books and Wikipedia
"The Triple Alliance War of 1865–70 was the most terrible ever fought in South America. It was a fiasco even for the winners—Argentina, Brazil, and Uruguay—and wreaked utter devastation on the loser, Paraguay. Ruled by Francisco Solano López, a dictator whom many believed insane, Paraguay had acquired a powerful army and maintained its standoffish attitude toward the outside world. Convinced that Argentina, Uruguay, and Brazil menaced his outlet to the sea through the Río de la Plata, López attacked first. The allies fought ostensibly in self-defense, supposedly to topple the dictator, but they also sought commercial, strategic, and territorial advantage. The armies of this war wore uniforms and used weapons like those of the contemporaneous US Civil War. Death tolls were similarly high. In a series of bloody battles, the allies ground the Paraguayans to a pulp. Paraguay’s adult male population practically vanished in the war. Brazil and Argentina both gained land at Paraguayan expense. But the war also generated a national mood of disillusionment in Brazil." [Born in Blood & Fire: A Concise History of Latin America, 4th Ed., p. 182]