The Paraguayan War, also known as the War of the Triple Alliance, was a South American war that lasted from 1864 to 1870. It was fought between Paraguay and the Triple Alliance of Argentina, the Empire of Brazil, and Uruguay. It was the deadliest and bloodiest inter-state war in Latin American history. Paraguay sustained large casualties, but the approximate numbers are disputed. Paraguay was forced to cede disputed territory to Argentina and Brazil. The war began in late 1864, as a result of a conflict between Paraguay and Brazil caused by the Uruguayan War. Argentina and Uruguay entered the war against Paraguay in 1865, and it then became known as the "War of the Triple Alliance."
The Battle of Curupayty was a key battle in the Paraguayan War. On the morning on 22 September 1866, the joint force of Brazilian, Argentine, and Uruguayan armies attacked Paraguayan fortified trenches on Curupayty. The Paraguayans were led by general José Eduvigis Díaz. This position was held by 5,000 men and 49 cannons, some of them in hidden places out of the attackers view. The Imperial Brazilian Navy gave support to the 20,000 assailants, but the ships had to keep some distance from the guns at the fortress of Humaitá, which led to the lack of accuracy and impact of the ship's fire. The navy's failure was crucial at the later ground battle result.
The Battle of Riachuelo was a large and decisive naval battle of the Paraguayan War between Paraguay and the Empire of Brazil. By late 1864, Paraguay had scored a series of victories in the war, but on 11 June 1865, its naval defeat by the Brazilians on the Paraná River began to turn the tide in favor of the allies.
The Battle of Tuyutí was a Paraguayan offensive in the Paraguayan War targeting the Triple Alliance encampment of Tuyutí. It is considered to be the bloodiest battle ever in South America. The result of the battle was an Allied victory, which added to the Paraguayan troubles after the loss of its fleet in the Battle of Riachuelo.
In the Paraguayan War, the Battle of Yatay was fought on August 17, 1865, between the troops of the Triple Alliance and the soldiers of Paraguay near Paso de los Libres, Corrientes, Argentina.
The Battle of Acosta Ñu or Campo Grande took place during the Paraguayan War, fought on 16 August 1869, between the Triple Alliance and Paraguay. The 3,500 poorly armed Paraguayans, mostly boys between nine and 15 years old, old men and wounded combatants, confronted 20,000 Brazilian and Argentine veteran soldiers.
The military history of Brazil comprises centuries of armed actions in the territory encompassing modern Brazil, and the role of the Brazilian Armed Forces in conflicts and peacekeeping worldwide. For several hundreds of years, the area was the site of intertribal wars of indigenous peoples. Beginning in the 16th century, the arrival of Portuguese explorers led to conflicts with the aboriginal peoples; a notable example being the revolt of the Tamoio Confederation. Sporadic revolts of African slaves also marked the colonial period, with a notable rebellion led by Zumbi dos Palmares. Conflicts were encountered with other European nations as well – two notable examples being the France Antarctique affair, and a conflict with the Netherlands in the early 17th century over control of much of the Northeast. Although Portugal retained its possessions during conflicts with other nations, it lost control of the colony after the Brazilian war of Independence, which led to the establishment of the Empire of Brazil.
Joaquín Madariaga was a soldier and Argentine politician. Madariaga was Governor of the Corrientes Province and leader of the provinces resistance against the national government of Juan Manuel de Rosas.
San Cosme y Damián is a district in the Itapúa Department of Paraguay. Located 80 km west of Encarnación, it is close to places like Ayolas, General Artigas or Isla Apipé, in Southern Paraguay and Northern Argentina, along the Paraná River, at the Argentina–Paraguay border. It covers an area of 800 km2 and has an estimated population of over 10,000 in 2023.
The Platine War was fought between the Argentine Confederation and an alliance consisting of the Empire of Brazil, Uruguay, and the Argentine provinces of Entre Ríos and Corrientes, with the participation of the Republic of Paraguay as Brazil's co-belligerent and ally. The war was part of a decades-long dispute between Argentina and Brazil for influence over Uruguay and Paraguay, and hegemony over the Platine region. The conflict took place in Uruguay and northeastern Argentina, and on the Río de la Plata. Uruguay's internal troubles, including the longrunning Uruguayan Civil War, were heavily influential factors leading to the Platine War.
The siege of Humaitá was a military operation in which the Triple Alliance flanked, besieged and captured the Fortress of Humaitá, a Paraguayan stronghold that was referred to as the Gibraltar of South America. It fell on 26 July 1868. It can be considered the key event of the Paraguayan War since the fortress had frustrated the allied advance into Paraguay for more than two years. However it did not surrender as the defenders escaped, most of them to fight another day.
The Battle of Curuzú occurred between September 1 and 3, 1866 during the Paraguayan War. After the first Battle of Tuyutí, won by the Allies on 24 May 1866, an Allied council of war decided to use their navy to bombard and capture the Paraguayan battery at Curupayty.
José Luís Mena Barreto was an army officer, politician and monarchist of the Empire of Brazil. He came from a wealthy family with a tradition of military service. José Luís entered the army in 1836, during the Ragamuffin War, a secessionist rebellion. The conflict lasted for almost ten years, and he fought in several military engagements at that time.
Events in the year 1866 in Brazil.
The Battle of Boquerón was fought on 16 July 1866 and the Battle of Sauce on 18 July 1866, between an allied force of Uruguayans, Brazilians, and Argentines on one side and Paraguay on the other in the Paraguayan War. The Spanish-born Uruguayan officer León de Pallejas (1816–1866) and the Paraguayan officer Elizardo Aquino were killed in the battle.
Events in the year 1867 in Paraguay.
The capture of the steamer Marquês de Olinda was a Paraguayan naval action carried out on 12 November 1864, in Potrero-Poña, on the Paraguay River, which consisted of the capture of the Brazilian merchant ship and all on board. Paraguayan president Solano López ordered the imprisonment in response to the Brazilian invasion of Uruguay, before any formal declaration of war between Paraguay and the Empire of Brazil.
The Battle of Paso de Patria was a battle of the Paraguayan War, which took place between April 16 to 23, 1866, on the banks of the Paraná River, in the then fortified position in Paso de Patria, in which the Empire of Brazil emerged victorious. It took place simultaneously with the Battle of Itapirú, during the so-called "crossing of the Paraná River".
The Battle of Itapirú took place during the Paraguayan War on April 17, 1866, after Brazil's capture of Purutué Bank a week earlier. The battle marked the beginning of the Triple Alliance's invasion of Paraguay.
The Humaitá campaign or the Cuadrilátero campaign was the third, longest and deadliest campaign of the Paraguayan War. The campaign lasted from 16 April 1866 to 5 August 1868. After the initial Paraguayan success in the Mato Grosso campaign and its failure in the Corrientes campaign, the armed forces of the Triple Alliance, Argentina, the Empire of Brazil and Uruguay, invaded the south of Paraguay. At a very short distance, they found the Paraguayan defensive device made up of four fortifications, the so-called "Cuadrilátero", which obstructed the passage to Asunción both by land and by the Paraguay River. A long series of battles cost huge numbers of casualties on both sides, with operations coming to a complete halt after the allied defeat at the Battle of Curupayty. Casualties on both sides were even higher from disease than from battle due to a cholera epidemic which was added to the appalling food and sanitary conditions.
Paraguay 
Empire of Brazil 
