The Battle of Curupaity was a key battle in the War of the Triple Alliance. Combatants Paraguay Uruguay, Argentina, Brasil Commanders Francisco Solano López Bartolomé Mitre, Marquês de Caxias Strength at the beginning of the war ca. ...

The Brazilian navy attacked Paraguayan forces led by General José E. Díaz on September 22, 1866. Camouflaged and fortified Paraguayan guns were situated above the riverbank where the Brazilian navy's guns could not reach. On land, the Paraguayan strategies were equally successful. A trench drew most of the Brazlian fire, but the Paraguayan troops were located elsewhere. Over 20 percent of the almost 20,000 allied (Brazilian and Argentine) troops involved in the attack were lost; Paraguay lost less than a hundred men. The utter failure resulted in the change of the allied command. Paraguay's biggest success in the ultimately disastrous War of the Triple Alliance was limited because its inept military leader Francisco Solano López didn't counterattack the defeated allies; not even a general as celebrated as Díaz would attack without López's orders. Ultimately, the battle of Curupaity was merely a sidenote and temporary success in what would eventually become a near-extermination of the Paraguayan people. September 22 is the 265th day of the year in the Gregorian calendar (266th in leap years). ... 1866 is a common year starting on Monday. ... Francisco Solano López Francisco Solano López (24 July 1827 - 1 March 1870) was president of Paraguay from 1862 until his death in 1870. ... Combatants Paraguay Uruguay, Argentina, Brasil Commanders Francisco Solano López Bartolomé Mitre, Marquês de Caxias Strength at the beginning of the war ca. ...

Source

Scheina, Robert L. Latin America's Wars: The Age of the Caudillo, 1791-1899. Brassey's: Dulles, Virgina. 2003.