Paraguayan War

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".

After Paraguay was defeated in conventional warfare, it conducted a drawn-out guerrilla resistance, a strategy that resulted in the further destruction of the Paraguayan military and the civilian population. Much of the civilian population lost their lives due to battle, hunger, and disease. The guerrilla war lasted for 14 months until President Francisco Solano López was killed in action by Brazilian forces in the Battle of Cerro Corá on 1 March 1870. Argentine and Brazilian troops occupied Paraguay until 1876.

Background

Territorial disputes

Since their independence from Portugal and Spain in the early 19th century, the Empire of Brazil and the Spanish-American countries of South America were troubled by territorial disputes. Each nation in this region had boundary conflicts with multiple neighbors. Most had overlapping claims to the same territories, due to unresolved questions which stemmed from their former metropoles. Signed by Portugal and Spain in 1494, the Treaty of Tordesillas proved ineffective in the following centuries, as both colonial powers expanded their frontiers in South America and elsewhere. The outdated boundary lines did not represent the actual occupation of lands by the Portuguese and Spanish.

By the early 1700s, the Treaty of Tordesillas was deemed not useful, and it was clear to both parties that a newer treaty had to be drawn based on feasible boundaries. In 1750, the Treaty of Madrid separated the Portuguese and Spanish areas of South America in lines that mostly corresponded to present-day boundaries. Neither Portugal nor Spain were satisfied with the results, and new treaties were signed in the following decades that either established new territorial lines or repealed them. The final accord signed by both powers, the Treaty of Badajoz (1801), reaffirmed the validity of the previous Treaty of San Ildefonso (1777), which had derived from the older Treaty of Madrid.

The territorial disputes became worse when the Viceroyalty of the Río de la Plata collapsed in the early 1810s, leading to the rise of Argentina, Paraguay, Bolivia, and Uruguay. Historian Pelham Horton Box writes: "Imperial Spain bequeathed to the emancipated Spanish-American nations not only her own frontier disputes with Portuguese Brazil but problems which had not disturbed her, relating to the exact boundaries of her own viceroyalties, captaincies general, audiencias and provinces." Once separated the three countries quarreled over lands that were mostly uncharted or unknown. They were either sparsely populated or settled by indigenous tribes that answered to no parties. In the case of Paraguay and Brazil, the problem was to define whether the Apa or Branco rivers should represent their actual boundary, a persistent issue that had confused Spain and Portugal in the late 18th century. A few indigenous tribes populated the region between the two rivers, and these tribes would attack Brazilian and Paraguayan settlements that were local to them.

Political situation before the war

There are several theories regarding the origins of the war. The traditional view emphasizes that the policies of Paraguayan President Francisco Solano López used the Uruguayan War as a pretext to gain control of the Platine basin. That caused a response from the regional hegemons, Brazil and Argentina, both of which exercised influence over the much smaller republics of Uruguay and Paraguay. The war has also been attributed to the aftermath of colonialism in South America with border conflicts between the new states, the struggle for power among neighboring nations over the strategic Río de la Plata region, Brazilian and Argentine meddling in internal Uruguayan politics (which had already caused the Platine War), Solano López's efforts to help his allies in Uruguay (which had been defeated by the Brazilians), and his presumed expansionist ambitions.

A strong military was developed because Paraguay's larger neighbors, Argentina and Brazil, had territorial claims against it and wanted to dominate it politically, much as both had already done in Uruguay. Paraguay had recurring boundary disputes and tariff issues with Argentina and Brazil for many years during the rule of Solano Lopez's predecessor and father, Carlos Antonio López.

Regional tension

In the time since Brazil and Argentina had become independent, their struggle for hegemony in the Río de la Plata region had profoundly marked the diplomatic and political relations among the countries of the region.

Brazil was the first country to recognize the independence of Paraguay, in 1844. At this time Argentina still considered it a breakaway province. While Argentina was ruled by Juan Manuel Rosas (1829–1852), a common enemy of both Brazil and Paraguay, Brazil contributed to the improvement of the fortifications and development of the Paraguayan army, sending officials and technical help to Asunción.

As no roads linked the inland province of Mato Grosso to Rio de Janeiro, Brazilian ships needed to travel through Paraguayan territory, going up the Paraguay River to arrive at Cuiabá. However, Brazil had difficulty obtaining permission from the government in Asunción to freely use the Paraguay River for its shipping needs.

Uruguayan prelude

Brazil had carried out three political and military interventions in the politically unstable Uruguay:
* in 1851 against Manuel Oribe in order to fight Argentine influence in the country and to end the Great Siege of Montevideo;
* in 1855, at the request of the Uruguayan government and Venancio Flores, leader of the Colorado Party, which was traditionally supported by the Brazilian empire;
* in 1864, against Atanasio Aguirre. This last intervention would lead to the Paraguayan War.

On 19 April 1863, Uruguayan General Venancio Flores, who was then an officer in the Argentine army as well as the leader of the Colorado Party of Uruguay, invaded his country, starting the '' Cruzada Libertadora'' with the open support of Argentina, which supplied the rebels with arms, ammunition and 2,000 men. Flores wanted to overthrow the Blanco Party government of President Bernardo Berro,Hooker, T.D., 2008, The Paraguayan War, Nottingham: Foundry Books, which was allied with Paraguay.

Paraguayan President López sent a note to the Argentine government on 6 September 1863, asking for an explanation, but Buenos Aires denied any involvement in Uruguay. From that moment, mandatory military service was introduced in Paraguay; in February 1864, an additional 64,000 men were drafted into the army.

One year after the beginning of the ''Cruzada Libertadora'', in April 1864, Brazilian minister José Antônio Saraiva arrived in Uruguayan waters with the Imperial Fleet, to demand payment for damages caused to Rio Grande do Sul farmers in border conflicts with Uruguayan farmers. Uruguayan President Atanasio Aguirre, from the Blanco Party, rejected the Brazilian demands, presented his own demands, and asked Paraguay for help. To settle the growing crisis, Solano López offered himself as a mediator of the Uruguayan crisis, as he was a political and diplomatic ally of the Uruguayan ''Blancos'', but the offer was turned down by Brazil.

Brazilian soldiers on the northern borders of Uruguay started to provide help to Flores' troops and harassed Uruguayan officers, while the Imperial Fleet pressed hard on Montevideo. During the months of June–August 1864 a Cooperation Treaty was signed between Brazil and Argentina at Buenos Aires, for mutual assistance in the Plate Basin Crisis.

Brazilian Minister Saraiva sent an ultimatum to the Uruguayan government on 4 August 1864: either comply with the Brazilian demands, or the Brazilian army would retaliate. The Paraguayan government was informed of all this and sent to Brazil a message, which stated in part:

The Brazilian government, probably believing that the Paraguayan threat would be only diplomatic, answered on 1 September, stating that "they will never abandon the duty of protecting the lives and interests of Brazilian subjects". But in its answer, two days later, the Paraguayan government insisted that "if Brazil takes the measures protested against in the note of August 30th, 1864, Paraguay will be under the painful necessity of making its protest effective."

On 12 October, despite the Paraguayan notes and ultimatums, Brazilian troops under the command of general João Propício Mena Barreto invaded Uruguay. This was not the start of the Paraguayan war, however, for Paraguay continued to maintain diplomatic relations with Brazil for another month.

On 11 November the Brazilian ship ''Marquês de Olinda'', on her routine voyage up the River Paraguay to the Brazilian Mato Grosso, and carrying the new governor of that province, docked at Asunción and took on coal. Completing the formalities, she continued on her journey. (According to one source, López hesitated whether to break the peace for a whole day, saying "If we don't have a war now with Brazil, we shall have one at a less convenient time for ourselves".) López then ordered the Paraguayan ship ''Tacuarí'' to pursue her and compel her return. On 12 November ''Tacuarí'' caught up with ''Marquês de Olinda'' in the vicinity of Concepción, fired across her bows, and ordered her to return to Asunción; when she arrived on the 13th, all on board were arrested. On the 12th Paraguay informed the Brazilian minister in Asunción that diplomatic relations had been broken off.

The conflict between Brazil and Uruguay was settled in February 1865. News of the war's end was brought by Pereira Pinto and met with joy in Rio de Janeiro. Brazilian Emperor Pedro II found himself waylaid by a crowd of thousands in the streets amid acclamations. However, public opinion quickly changed for the worse when newspapers began running stories painting the convention of 20 February as harmful to Brazilian interests, for which the cabinet was blamed. The newly raised Viscount of Tamandaré and Mena Barreto (now Baron of São Gabriel) had supported the peace accord. Tamandaré changed his mind soon afterward and played along with the allegations. A member of the opposition party, José Paranhos, Viscount of Rio Branco, was used as a scapegoat by the Emperor and the government and was recalled in disgrace to the imperial capital. The accusation that the convention had failed to meet Brazilian interests proved to be unfounded. Not only had Paranhos managed to settle all Brazilian claims, but by preventing the death of thousands, he gained a willing and grateful Uruguayan ally instead of a dubious and resentful one, which provided Brazil with an important base of operations during the acute clash with Paraguay that shortly ensued.

Opposing forces

Paraguay

According to some historians, Paraguay began the war with over 60,000 trained men—38,000 of whom were already under arms—400 cannons, a naval squadron of 23 steamboats (''vapores'') and five river-navigating ships (among them the ''Tacuarí'' gunboat).

Communications in the Río de la Plata basin were maintained solely by the river as very few roads existed. Whoever controlled the rivers would win the war, so Paraguay had built fortifications on the banks of the lower end of the Paraguay River.

However, recent studies suggest many problems. Although the Paraguayan army had between 70,000 and 100,000 men at the beginning of the conflict, they were badly equipped. Most infantry armaments consisted of inaccurate smooth-bore muskets and carbines, slow to reload and short-ranged. The artillery was similarly poor. Military officers had no training or experience, and there was no command system, as all decisions were made personally by López. Food, ammunition, and armaments were scarce, with logistics and hospital care deficient or nonexistent. The nation of about 450,000 people could not stand against the Triple Alliance of 11 million people.

Brazil and its allies

At the beginning of the war, the military forces of Brazil, Argentina, and Uruguay were far smaller than Paraguay's. Argentina had approximately 8,500 regular troops and a naval squadron of four ''vapores'' and one ''goleta''. Uruguay entered the war with fewer than 2,000 men and no navy. Many of Brazil's 16,000 troops were located in its southern garrisons. The Brazilian advantage, though, was in its navy, comprising 45 ships with 239 cannons and about 4,000 well-trained crew. A great part of the squadron was already in the Rio de la Plata basin, where it had acted under the Marquis of Tamandaré in the intervention against Aguirre government.

Brazil, however, was unprepared to fight a war. Its army was disorganized. The troops it used in Uruguay were mostly armed contingents of gauchos and the National Guard. While some Brazilian accounts of the war described their infantry as volunteers (''Voluntários da Pátria''), other Argentine revisionist and Paraguayan accounts disparaged the Brazilian infantry as mainly recruited from slaves and the landless (largely black) underclass, who were promised free land for enlisting. The cavalry was formed from the National Guard of Rio Grande do Sul.

Ultimately, a total of about 146,000 Brazilians fought in the war from 1864 to 1870, consisting of the 10,025 army soldiers stationed in Uruguayan territory in 1864, 2,047 that were in the province of Mato Grosso, 55,985 Fatherland Volunteers, 60,009 National Guardsmen, 8,570 ex-slaves who had been freed to be sent to war, and 9,177 navy personnel. Another 18,000 National Guard troops stayed behind to defend Brazilian territory.

Course of the war

Battles

Paraguayan offensive in Mato Grosso

Paraguay took the initiative during the first phase of the war, launching the Mato Grosso Campaign by invading the Brazilian province of Mato Grosso on 14 December 1864, followed by an invasion of the Rio Grande do Sul province in the south in early 1865 and the Argentine Corrientes Province.

Two separate Paraguayan forces invaded Mato Grosso simultaneously. An expedition of 3,248 troops, commanded by Col. Vicente Barrios, was transported by a naval squadron under the command of ''Capitán de Fragata'' Pedro Ignacio Meza up the Paraguay River to the town of Concepcion. There they attacked the Nova Coimbra fort on 27 December 1864. The Brazilian garrison of 154 men resisted for three days, under the command of Lt. Col. Hermenegildo Portocarrero (later Baron of Fort Coimbra). When their munitions were exhausted, the defenders abandoned the fort and withdrew up the river towards Corumbá on board the gunship ''Anhambaí''. After occupying the fort, the Paraguayans advanced further north, taking the cities of Albuquerque, Tage and Corumbá in January 1865.

Solano López then sent a detachment to attack the military frontier post of Dourados. On 29 December 1864, this detachment, led by Maj. Martín Urbieta, encountered tough resistance from Lt. Antônio João Ribeiro and his 16 men, who were all eventually killed. The Paraguayans continued to Nioaque and Miranda, defeating the troops of Col. José Dias da Silva. Coxim was taken in April 1865. The second Paraguayan column, formed from some of the 4,650 men led by Col. Francisco Isidoro Resquín at Concepcion, penetrated into Mato Grosso with 1500 troops.

Despite these victories, the Paraguayan forces did not continue to Cuiabá, the capital of the province, where Augusto Leverger had fortified the camp of Melgaço. Their main objective was the capture of the gold and diamond mines, disrupting the flow of these materials into Brazil until 1869.

Brazil sent an expedition to fight the invaders in Mato Grosso. A column of 2,780 men led by Col. Manuel Pedro Drago left Uberaba in Minas Gerais in April 1865 and arrived at Coxim in December, after a difficult march of more than through four provinces. However, Paraguay had already abandoned Coxim by December. Drago arrived at Miranda in September 1866, and Paraguayans had left once again. Col. Carlos de Morais Camisão assumed command of the column in January 1867—now with only 1,680 men—and decided to invade Paraguayan territory, which he penetrated as far as Laguna where Paraguayan cavalry forced the expedition to retreat.

Despite the efforts of Camisão's troops and the resistance in the region, which succeeded in liberating Corumbá in June 1867, a large portion of Mato Grosso remained under Paraguayan control. The Brazilians withdrew from the area in April 1868, moving their troops to the main theatre of operations, in the south of Paraguay.

Paraguayan invasion of Corrientes and Rio Grande do Sul

When the war first broke out between Paraguay and Brazil, Argentina stayed neutral. Solano López doubted Argentina's neutrality because it gave Brazilian ships permission to navigate in the Argentine rivers of the Plate region, despite Paraguay being at war with Brazil.

The invasion of Corrientes and the Rio Grande do Sul provinces was the second phase of the Paraguayan offensive. In order to support the Uruguayan Blancos, the Paraguayans had to travel across the Argentine territory. In January 1865, Solano López asked Argentina's permission for an army of 20,000 men (led by Gen. Wenceslao Robles) to travel through the province of Corrientes. Argentine President Bartolomé Mitre refused Paraguay's request and a similar one from Brazil.

After this refusal Paraguayan Congress gathered at an emergency meeting on 5 March 1865. After several days of discussions, on 23 March the Congress decided to declare war on Argentina for its policies, hostile to Paraguay and favourable to Brazil, and then they conferred to Francisco Solano López Carrillo the rank of ''Field Marshal'' of the Republic of Paraguay. The declaration of war was sent on 29 March 1865 to Buenos Aires.

On 13 April 1865, a Paraguayan squadron sailed down the Paraná River and attacked two Argentine ships in the port of Corrientes. Immediately Gen. Robles' troops took the city with 3,000 men, and a cavalry force of 800 arrived the same day. Leaving a force of 1,500 men in the city, Robles advanced southwards along the eastern bank.

Along with Robles' troops, a force of 12,000 soldiers under Col. Antonio de la Cruz Estigarribia crossed the Argentine border south of Encarnación in May 1865, driving for Rio Grande do Sul. They traveled down Uruguay River and took the town of São Borja on 12 June. Uruguaiana, to the south, was taken on 6 August with little resistance.

By invading Corrientes, Solano López had hoped to gain the support of the powerful Argentine '' caudillo'' Justo José de Urquiza, governor of the provinces of Corrientes and Entre Ríos, who was known to be the chief federalist hostile to Mitre and the central government in Buenos Aires. However, Urquiza gave his full support to an Argentine offensive. The forces advanced approximately south before ultimately ending the offensive in failure.

Following the invasion of the Corrientes Province by Paraguay on 13 April 1865, a great uproar stirred in Buenos Aires as the public learned of Paraguay's declaration of war. President Bartolomé Mitre made a famous speech to the crowds on 4 May 1865:

The same day, Argentina declared war on Paraguay; however, on 1 May 1865, Brazil, Argentina, and Uruguay had signed the secret Treaty of the Triple Alliance in Buenos Aires. They named Bartolomé Mitre, president of Argentina, as supreme commander of the allied forces. The signatories of the treaty were Rufino de Elizalde (Argentina), Otaviano de Almeida (Brazil) and Carlos de Castro (Uruguay).

On 11 June 1865, at the naval Battle of Riachuelo, the Brazilian fleet commanded by Admiral Francisco Manoel Barroso da Silva destroyed the Paraguayan navy and prevented the Paraguayans from permanently occupying Argentine territory. For all practical purposes, this battle decided the outcome of the war in favor of the Triple Alliance; from that point onward, it controlled the waters of the Río de la Plata basin up to the entrance to Paraguay.

A separate Paraguayan division of 3,200 men that continued towards Uruguay under the command of Maj. Pedro Duarte, who was then defeated by Allied troops under Venancio Flores in the bloody Battle of Yatay, on the banks of the Uruguay River, near Paso de los Libres.

Siege of Uruguaiana

While Solano López ordered the retreat of the forces that had occupied Corrientes, the Paraguayan troops that invaded São Borja advanced, taking Itaqui and Uruguaiana. The situation in Rio Grande do Sul was chaotic, and the local Brazilian military commanders were incapable of mounting effective resistance to the Paraguayans.

The baron of Porto Alegre set out for Uruguaiana, a small town in the province's west, where the Paraguayan army was besieged by a combined force of Brazilian, Argentine and Uruguayan units. Porto Alegre assumed the command of the Brazilian army in Uruguaiana on 21 August 1865. On 18 September, the Paraguayan garrison surrendered without further bloodshed.

Allied counterattack

Invasion of Paraguay

In subsequent months, the Paraguayans were driven out of the cities of Corrientes and San Cosme, the only Argentine territory still in Paraguayan possession.

By the end of 1865, the Triple Alliance was on the offensive. Its armies numbered 42,000 infantry and 15,000 cavalry as they invaded Paraguay in April. The Paraguayans scored small victories against major forces in the Battle of Corrales (also known as battle of Pehuajó or Itati) in the Corrientes Province, but that couldn't stop the invasion.

On 16 April 1866, the Allied Armies invaded Paraguayan mainland by crossing the Paraná River. López launched counter-attacks, but they were repelled by Gen. Manuel Luís Osório, who took victories in the battles of Itapirú and Isla Cabrita. Yet, the Allied advance was checked in the first major battle of the war, at Estero Bellaco, on 2 May 1866.

López, believing that he could deal a fatal blow to the Allies, launched a major offensive with 25,000 men against 35,000 Allied soldiers at the Battle of Tuyutí on 24 May 1866, one of the bloodiest battles in Latin-American history. Despite being very close to victory at Tuyutí, López's plan was shattered by the Allied army's fierce resistance and the decisive action of the Brazilian artillery. Both sides sustained heavy losses: more than 12,000 casualties for Paraguay versus 6,000 for the Allies.

By 18 July, the Paraguayans had recovered, defeating forces commanded by Mitre and Flores in the Battle of Sauce and Boquerón, losing more than 2,000 men against the Allied 6,000 casualties. However, Brazilian Gen. Porto Alegre won the Battle of Curuzú, putting the Paraguayans in a desperate situation.

On 12 September 1866, Solano López, after the defeat in the Battle of Curuzú, invited Mitre and Flores to a conference in Yataytí Corá, which resulted in a "heated argument" among both leaders. López had realized that the war was lost and was ready to sign a peace treaty with the Allies. No agreement was reached, though, since Mitre's conditions for signing the treaty were that every article of the secret Treaty of the Triple Alliance was to be carried out, a condition that Solano López refused. Article 6 of the treaty made truce or peace with López nearly impossible, as it stipulated that the war was to continue until the then government ceased to be, which meant the removal of Solano López.

After the conference, the Allies marched into Paraguayan territory, reaching the defensive line of Curupayty. Trusting in their numerical superiority and the possibility of attacking the flank of the defensive line through the Paraguay River by using the Brazilian ships, the Allies made a frontal assault on the defensive line, supported by the flank fire of the battleships. However, the Paraguayans, commanded by General José E. Díaz, stood strong in their positions and set up for a defensive battle, inflicting tremendous damage on the attacking Allied troops, inflicting over 8,000 casualties on the Brazil-Argentine army against no more than 250 losses of the Paraguayans. The Battle of Curupayty resulted in an almost catastrophic defeat for the Allied forces, ending their offensive for ten months, until July 1867.

The Allied leaders blamed each other for disastrous failure at Curupayty. General Flores left for Uruguay in September 1866 shortly after the battle and was later murdered there in 1867. Porto Alegre and Tamandaré found common ground in their distaste for the Brazilian commander of the 1st Corps, field marshal , Viscount of Santa Teresa. General Jordão was ostracized for supporting Mitre and for being a member of the Conservative Party, while Porto Alegre and Tamandaré were Progressives.

General Porto Alegre also blamed Mitre for the tremendous defeat, saying:

Mitre had a harsh opinion of the Brazilians and said that "Porto Alegre and Tamandaré, who are cousins, and cousins even in lack of judgement have made a family pact to monopolize, in practice, the command of war." He further criticized Porto Alegre: "It is impossible to imagine a greater military nullity than this general, to which it can be added Tamandaré's dominating bad influence over him and the negative spirit of both in relation to the allies, owning to passions and petty interests."

Caxias assumes command

The Brazilian government decided to create a unified command over Brazilian forces operating in Paraguay, and turned to the 63-year-old Caxias as the new leader on the 10 of October 1866. Osório was sent to organize a 5,000-strong third corps of the Brazilian army in Rio Grande do Sul. Caxias arrived in Itapiru on the 17 of November. His first measure was to dismiss the Vice-Admiral Joaquim Marques Lisboa (later the Marquis of Tamandaré and also a member of the Progressive League). The government had appointed his fellow Conservative Vice-Admiral, Joaquim José Inácio—later the Viscount of Inhaúma—to lead the navy.

The Marquess of Caxias assumed command on 19 November. He aimed to end the never-ending squabbling and to increase his autonomy from the Brazilian government. With the departure of President Mitre in February 1867, Caxias assumed overall command of the Allied forces. He found the army practically paralyzed and devastated by disease. During this period Caxias trained his soldiers, re-equipped the army with new guns, improved the quality of the officer corps, and upgraded the health corps and overall hygiene of the troops, putting an end to epidemics. From October 1866 until July 1867, all offensive operations were suspended. Military operations were limited to skirmishes with the Paraguayans and bombarding Curupaity. Solano López took advantage of the disorganization of the enemy to reinforce the Fortress of Humaitá.

As the Brazilian army was ready for combat, Caxias sought to encircle Humaitá and force its capitulation by siege. To aid the war effort, Caxias used observation balloons to gather information of the enemy lines. With the 3rd Corps ready for combat, the Allied army started its flanking march around Humaitá on 22 July. The march to outflank the left-wing of the Paraguayan fortifications constituted the basis of Caxias' tactics. He wanted to bypass the Paraguayan strongholds, cut the connections between Asunción and Humaitá and finally encircle the Paraguayans. The 2nd Corps was stationed in Tuyutí, while the 1st corps and the newly created 3rd Corps were used by Caxias to encircle Humaitá. President Mitre returned from Argentina and re-assumed overall command on 1 August. With the capture on 2  November by Brazilians troops of the Paraguayan position of Tahí, at the shores of the river, Humaitá would become isolated from the rest of the country by land.

Allies gain momentum

Fall of Humaitá

The combined Brazilian–Argentine–Uruguayan army continued advancing north through hostile territory to surround Humaitá. The Allied force advanced to San Solano on the 29th and Tayi on 2 November, isolating Humaitá from Asunción. Before dawn on 3 November, Solano López reacted by ordering the attack on the rearguard of the allies in the Second Battle of Tuyutí.

The Paraguayans, commanded by General Bernardino Caballero breached the Argentine lines, causing enormous damage to the Allied camp and successfully capturing weapons and supplies, very needed by López for the war effort. Only thanks to the intervention of Porto Alegre and his troops, the Allied army recovered. During the Second Battle of Tuyutí, Porto Alegre fought with his saber in hand-to-hand combat and lost two horses. In this battle, the Paraguayans lost over 2,500 men, while the allies had just over 500 casualties.

By 1867, Paraguay had lost 60,000 men to battle casualties, injuries, or disease. Due to the growing manpower shortage, López conscripted another 60,000 soldiers from slaves and children. Women were entrusted with all support functions alongside the soldiers. Many Paraguayan soldiers went into battle without shoes or uniforms. López enforced the strictest discipline, executing even his two brothers and two brothers-in-law for alleged defeatism.

By December 1867, there were 45,791 Brazilians, 6,000 Argentines and 500 Uruguayans at the front. After the death of Argentine Vice-President Marcos Paz, Mitre relinquished his position for the second, and final time on 14 January 1868. Allied representatives in Buenos Aires abolished the position of Allied commander-in-chief on 3 October, although the Marquess of Caxias continued to fill the role of Brazilian supreme commander.

On 19 February, Brazilian ironclads successfully made a passage up the Paraguay River under heavy fire, gaining full control of the river and isolating Humaitá from resupply by water. Humaitá fell on 25 July 1868, after a long siege.

Assault on the battleships Cabral and Lima Barros

The assault on the warships '' Lima Barros'' and '' Cabral'' was a naval action that took place in the early hours of 2 March 1868, when Paraguayan canoes, joined two by two, disguised with branches and manned by 50 soldiers each, approached the ironclads ''Lima Barros'' and ''Cabral''. The Imperial Fleet, which had already achieved the Passage of Humaitá, was anchored in the Paraguay river, before the Taji stronghold near Humaitá.

Taking advantage of the dense darkness of the night and the camalotes and rafters that descended on the current, a squadron of canoes covered by branches and foliage and tied two by two, crewed by 1,500 Paraguayans armed with machetes, hatchets and approaching swords, went to approach ''Cabral'' and ''Lima Barros''. The fighting continued until dawn when the warships ''Brasil'', '' Herval'', ''Mariz e Barros'' and ''Silvado'' approached and shot the Paraguayans, who gave up the attack, losing 400 men and 14 canoes.

First Battle of Iasuií

The First Battle of Iasuií took place on 2 May 1868, between Brazilians and Paraguayans, in the Chaco region of Paraguay. On the occasion, Colonel Barros Falcão, the head of a garrison of 2,500 soldiers, repelled a Paraguayan attack, suffering 137 casualties. The attackers lost 105 soldiers.

Fall of Asunción

''En route'' to Asunción, the Allied army went north to Palmas, stopping at the Piquissiri River. There Solano López had concentrated 12,000 Paraguayans in a fortified line that exploited the terrain and supported the forts of Angostura and Itá-Ibaté.

Resigned to frontal combat, Caxias ordered the so-called Piquissiri maneuver. While a squadron attacked Angostura, Caxias made the army cross to the west side of the river. He ordered the construction of a road in the swamps of the Gran Chaco along which the troops advanced to the northeast. At Villeta the army crossed the river again, between Asunción and Piquissiri, behind the fortified Paraguayan line.

Instead of advancing to the capital, already evacuated and bombarded, Caxias went south and attacked the Paraguayans from the rear in December 1868, in an offensive which became known as "Dezembrada". Caxias' troops were ambushed while crossing the Itororó during an initial advance, during which the Paraguayans inflicted severe damage on the Brazilian armies. Days later, however, the Allies destroyed a whole Paraguayan division at the Battle of Avay. Weeks later, Caxias won another decisive victory at the Battle of Lomas Valentinas and captured the last stronghold of the Paraguayan Army in Angostura. On 24 December, Caxias sent a note to Solano López asking for surrender, but Solano López refused and fled to Cerro León. Alongside the Paraguayan president was the American Minister-Ambassador, Gen. Martin T. McMahon, who after the war became a fierce defender of López's cause.

Asunción was occupied on 1 January 1869, by Brazilian Gen. João de Souza da Fonseca Costa, father of the future Marshal Hermes da Fonseca. On 5 January, Caxias entered the city with the rest of the army. Most of Caxias army settled in Asunción, where also 4000 Argentine and 200 Uruguayan troops soon arrived together with about 800 soldiers and officers of the Paraguayan Legion. By this time, Caxias was ill and tired. On 17 January, he fainted during a Mass; he relinquished his command the next day, and the day after that left for Montevideo.

Very soon the city hosted about 30,000 Allied soldiers; for the next few months these looted almost every building, including diplomatic missions of European nations.

Provisional government

With Solano López on the run, the country lacked a government. Pedro II sent his Foreign minister José Paranhos to Asunción where he arrived on 20 February 1869 and began consultations with the local politicians. Paranhos had to create a provisional government that could sign a peace accord and recognize the border claimed by Brazil between the two nations. According to historian Francisco Doratioto, Paranhos, "the then-greatest Brazilian specialist on Platine affairs", had a "decisive" role in the installation of the Paraguayan provisional government.

With Paraguay devastated, the power vacuum resulting from Solano López's overthrow was quickly filled by emerging domestic factions which Paranhos had to accommodate. On 31 March, a petition was signed by 335 leading citizens asking Allies for a Provisional government. This was followed by negotiations between the Allied countries, which put aside some of the more controversial points of the Treaty of the Triple Alliance; on 11 June, agreement was reached with Paraguayan opposition figures that a three-man Provisional government would be established. On 22 July, a National Assembly met in the National Theatre and elected ''Junta Nacional'' of 21 men which then selected a five-man committee to select three men for the Provisional government. They selected Carlos Loizaga, Juan Francisco Decoud, and José Díaz de Bedoya. Decoud was unacceptable to Paranhos, who had him replaced with Cirilo Antonio Rivarola. The government was finally installed on 15 August, but was just a front for the continued Allied occupation. After the death of Lopez, the Provisional Government issued a proclamation on 6 March 1870 in which it promised to support political liberties, to protect commerce and to promote immigration.

The Provisional Government did not last. In May 1870, José Díaz de Bedoya resigned; on 31 August 1870, so did Carlos Loizaga. The remaining member, Antonio Rivarola, was then immediately relieved of his duties by the National Assembly, which established a provisional Presidency, to which it elected Facundo Machaín, who assumed his post that same day. However, the next day, 1 September, he was overthrown in a ''coup'' that restored Rivarola to power.

End of the war

Campaign of the Hills

The son-in-law of Emperor Pedro II, Gaston, Count of Eu, was nominated in 1869 to direct the final phase of the military operations in Paraguay. At the head of 21,000 men, Eu led the campaign against the Paraguayan resistance, the Campaign of the Hills, which lasted over a year.

Most important were the Battle of Piribebuy and the Battle of Acosta Ñu, in which more than 5,000 Paraguayans died. After a successful beginning which included victories over the remnants of Solano López's army, the Count fell into depression and Paranhos became the unacknowledged, de facto commander-in-chief.

Death of Solano López

President Solano López organized the resistance in the mountain range northeast of Asunción. At the end of the war, with Paraguay suffering severe shortages of weapons and supplies, Solano López reacted with draconian attempts to keep order, ordering troops to kill any of their colleagues, including officers, who talked of surrender. Paranoia prevailed in the army, and soldiers fought to the bitter end in a resistance movement, resulting in more destruction in the country.

Two detachments were sent in pursuit of Solano López, who was accompanied by 200 men in the forests in the north. On 1 March 1870, the troops of General José Antônio Correia da Câmara surprised the last Paraguayan camp in Cerro Corá. During the ensuing battle, Solano López was wounded and separated from the remainder of his army. Too weak to walk, he was escorted by his aide and a pair of officers, who led him to the banks of the Aquidaban-nigui River. The officers left Solano López and his aide there while they looked for reinforcements.

Before they returned, Câmara arrived with a small number of soldiers. Though he offered to permit Solano López to surrender and guaranteed his life, Solano López refused. Shouting "I die with my homeland!", he tried to attack Câmara with his sword. He was quickly killed by Câmara's men, bringing an end to the long conflict in 1870.

Casualties of the war

Paraguay suffered massive casualties, and the war's disruption and disease also cost civilian lives. Some historians estimate that the nation lost the majority of its population. The specific numbers are hotly disputed and range widely. A survey of 14 estimates of Paraguay's pre-war population varied between 300,000 and 1,337,000. Later academic work based on demographics produced a wide range of estimates, from a possible low of 21,000 (7% of population) (Reber, 1988) to as high as 69% of the total prewar population (Whigham, Potthast, 1999). Because of the local situation, all casualty figures are a very rough estimate; accurate casualty numbers may never be determined.

After the war, an 1871 census recorded 221,079 inhabitants, of which 106,254 were women, 28,746 were men, and 86,079 were children (with no indication of sex or upper age limit).

The worst reports are that up to 90% of the male population was killed, though this figure is without support. One estimate places total Paraguayan losses—through both war and disease—as high as 1.2 million people, or 90% of its pre-war population, but modern scholarship has shown that this number depends on a population census of 1857 that was a government invention. A different estimate places Paraguayan deaths at approximately 300,000 people out of 500,000 to 525,000 pre-war inhabitants. During the war, many men and boys fled to the countryside and forests.

In the estimation of Vera Blinn Reber, however, "The evidence demonstrates that the Paraguayan population casualties due to the war have been enormously exaggerated".

A 1999 study by Thomas Whigham from the University of Georgia and Barbara Potthast (published in the ''Latin American Research Review'' under the title "The Paraguayan Rosetta Stone: New Evidence on the Demographics of the Paraguayan War, 1864–1870", and later expanded in the 2002 essay titled "Refining the Numbers: A Response to Reber and Kleinpenning") used a methodology to yield more accurate figures. To establish the population before the war, Whigham used an 1846 census and calculated, based on a population growth rate of 1.7% to 2.5% annually (which was the standard rate at that time), that the immediately pre-war Paraguayan population in 1864 was approximately 420,000–450,000. Based on a census carried out after the war ended, in 1870–1871, Whigham concluded that 150,000–160,000 Paraguayan people had survived, of whom only 28,000 were adult males. In total, 60–70% of the population died as a result of the war, leaving a woman/man ratio of 4 to 1 (as high as 20 to 1, in the most devastated areas). For academic criticism of the Whigham-Potthast methodology and estimates see the main article Paraguayan War casualties.

Steven Pinker wrote that, assuming a death rate of over 60% of the Paraguayan population, this war was proportionally one of the most destructive in modern times for any nation state. Steven Pinker

Allied losses

Of approximately 123,000 Brazilians who fought in the Paraguayan War, the best estimates are that around 50,000 men died. Uruguay had about 5,600 men under arms (including some foreigners), of whom about 3,100 died. Argentina lost close to 30,000 men.

The high rates of mortality were not all due to combat. As was common before antibiotics were developed, disease caused more deaths than war wounds. Bad food and poor sanitation contributed to disease among troops and civilians. Among the Brazilians, two-thirds of the dead died either in a hospital or on the march. At the beginning of the conflict, most Brazilian soldiers came from the north and northeast regions; the change from a hot to a colder climate, combined with restricted food rations, may have weakened their resistance. Entire battalions of Brazilians were recorded as dying after drinking water from rivers. Therefore, some historians believe cholera, transmitted in the water, was a leading cause of death during the war.

Gender and ethnic aspects

Women in the Paraguayan War

Paraguayan women played a significant role in the Paraguayan War. During the period just before the war began many Paraguayan women were the heads of their households, meaning they held a position of power and authority. They received such positions by being widows, having children out of wedlock, or their husbands having worked as ''peons''. When the war began women started to venture out of the home becoming nurses, working with government officials, and establishing themselves into the public sphere. When ''The New York Times'' reported on the war in 1868, it considered Paraguayan women equal to their male counterparts.

Paraguayan women's support of the war effort can be divided into two stages. The first is from the time the war began in 1864 to the Paraguayan evacuation of Asunción in late 1868. During this period of the war, peasant women became practically the sole producers of agricultural goods. The second stage begins when the war turned to a more guerrilla form; it started when the capital of Paraguay fell and ended with the death of Paraguay's president Francisco Solano López in 1870. At this stage, the number of women becoming victims of war was increasing. The government press, with doubtful veracity, claimed that battalions of women were formed to fight the Allies and exalted the role of Ramona Martínez (who was a woman enslaved by López) as "the American Joan of Arc" for her fighting and rallying of injured troops., pp. 36–37.

Women helped sustain Paraguayan society during a very unstable period. Though Paraguay did lose the war, the outcome might have been even more disastrous without women performing specific tasks. Women worked as farmers, soldiers, nurses, and government officials. They became a symbol for national unification, and at the end of the war, the traditions women maintained were part of what held the nation together.

A 2012 piece in ''The Economist'' argued that with the death of most of Paraguay's male population, the Paraguayan War distorted the sex ratio to women greatly outnumbering men and has impacted the sexual culture of Paraguay to this day. Because of the depopulation, men were encouraged after the war to have multiple children with multiple women, even supposedly celibate Catholic priests. A columnist linked this cultural idea to the paternity scandal of former president Fernando Lugo, who fathered multiple children while he was a supposedly celibate priest.

Paraguayan indigenous people

Prior to the war, indigenous people occupied very little space in the minds of the Paraguayan elite. Paraguayan president Carlos Antonio Lopez even modified the country's constitution in 1844 to remove any mention of Paraguay's Hispano-Guarani character. This marginalization was undercut by the fact that Paraguay had long prized its military as its only honorable and national institution and the majority of the Paraguayan military was indigenous and spoke Guarani. However, during the war, the indigenous people of Paraguay came to occupy an even larger role in public life, especially after the Battle of Estero Bellaco. For this battle, Paraguay put its "best" men, who happened to be of Spanish descent, front and center. Paraguay overwhelmingly lost this battle, as well as "the males of all the best families in the country." The now remaining members of the military were "old men who had been left in Humaita, Indians, slaves and boys."

The war also bonded the indigenous people of Paraguay to the project of Paraguayan nation-building. In the immediate lead up to the war, they were confronted with a barrage of nationalist rhetoric (in Spanish and Guarani) and subject to loyalty oaths and exercises. Paraguayan president Francisco Solano Lopez, son of Carlos Antonio Lopez, was well aware that the Guarani speaking people of Paraguay had a group identity independent of the Spanish-speaking Paraguayan elite. He knew he would have to bridge this divide or risk it being exploited by the 'Triple Alliance.' To a certain extent, Lopez succeeded in getting the indigenous people to expand their communal identity to include all of Paraguay. As a result of this, any attack on Paraguay was considered to be an attack on the Paraguayan nation, despite rhetoric from Brazil, Uruguay and Argentina saying otherwise. This sentiment increased after the terms of the Treaty of the Triple Alliance were leaked, especially the clause stating that Paraguay would pay for all the damages incurred by the conflict.

Afro-Brazilians

The Brazilian government allowed the creation of black-only units or "''zuavos''" in the military at the outset of the war, following the proposal of Afro-Brazilian Quirino Antônio do Espírito Santo, a veteran of the Brazilian War of Independence. Over the course of the war, the ''zuavos'' became an increasingly attractive option for many enslaved Afro-Brazilian men, especially given the z''uavos''’ negative opinion toward slavery. Once the ''zuavos'' had enlisted or forcibly recruited them, it became difficult for their masters to regain possession of them, since the government was desperate for soldiers. By 1867, black-only units were no longer permitted, with the entire military being integrated just as it had been prior to the war. The overarching rationale behind this was that the "country needed recruits for its existing battalions, not more independently organized companies." This did not mean the end of black soldiers in the Brazilian military. On the contrary, "impoverished ''gente de cor'' constituted the greater part of the soldiers in every Brazilian infantry battalion."

Afro-Brazilian women played a key role in sustaining the Brazilian military as "''vivandeiras''." ''Vivandeiras'' were poor women who traveled with the soldiers to perform "logistic tasks such as carrying tents, preparing food and doing laundry." For most of these women, the principal reason they became vivandeiras was because their male loved ones had joined as soldiers and they wanted to take care of them. However, the Brazilian government actively worked to minimize the importance of their work by labeling it "service to their male kin, not the nation" and considering it to be "natural" and "habitual." The reality was that the government depended heavily on these women and officially required their presence in the camps. Poor Afro-Brazilian women also served as nurses, with most of them being trained upon entry into the military to assist male doctors in the camps. These women were "seeking gainful employment to compensate for the loss of income from male kin who had been drafted into the war."

Territorial changes and treaties

Paraguay permanently lost its claim to territories which, before the war, were in dispute between it and Brazil or Argentina, respectively. In total, about were affected. Those disputes had been longstanding and complex.

Disputes with Brazil

In colonial times certain lands lying to the north of the River Apa were in dispute between the Portuguese Empire and the Spanish Empire. After independence they continued to be disputed between the Empire of Brazil and the Republic of Paraguay.

After the war Brazil signed a separate Loizaga–Cotegipe Treaty of peace and borders with Paraguay on 9 January 1872, in which it obtained freedom of navigation on the Paraguay River. Brazil also retained the northern regions it had claimed before the war. Those regions are now part of its State of Mato Grosso do Sul.

Disputes with Argentina

Misiones

In colonial times the missionary Jesuits established numerous villages in lands between the rivers Paraná and Uruguay. After the Jesuits were expelled from Spanish territory in 1767, the ecclesiastical