--- title: "The Paraguayan War: South America's Most Devastating Conflict" description: "Often overlooked in the history books, the Paraguayan War, also known as the War of the Triple Alliance, is a crucial piece of Latin American history. The war lasted more than five years, involved four separate countries, and was one of the deadliest conflicts of all time. The battles played out on both land and sea, and its bloody resolution helped shape South America as we know it today. What began as meddling in Uruguayan politics escalated into a war of annihilation that would claim as much as 60% of Paraguay's entire pre-war population and leave the country without fathers and husbands for a generation.\n\n## Key Takeaways\n- Paraguay lost an estimated 60% of its entire pre-war population and up to 90% of its male population during the five-year conflict.\n- The Battle of Tuyutí remains the bloodiest single battle in South American history, with Paraguay suffering 6,000 dead and 7,000 wounded in just four hours.\n- The Treaty of the Triple Alliance's Article 6 bound Brazil, Argentina, and Uruguay to fight until Paraguay's government was completely overthrown.\n- Admiral Francisco Barroso turned the Battle of Riachuelo by personally ramming four Paraguayan ships with the steam frigate Amazonas, sinking or disabling them.\n- At Curupayty, the Allies suffered over 4,000 casualties while Paraguay lost only 92, the most lopsided battle of the war.\n\n## A Continent in Turmoil: The Roots of Conflict\n\nThe 19th century was a tumultuous time for Latin America. One after another, countries were slipping out of the control of their colonial powers, forging their own identities as independent nations. Now being able to govern themselves, and with Spain and Portugal no longer taking a hefty 20% tax on all goods, it seemed that each country had a chance to stand on its own two legs. But the colonial powers had left behind a bit of a mess in the continent when they left without marking clear borders between nations, and now every country had a territorial dispute with its neighbors. In some places, three countries all claimed the same piece of land, and they often fought over these. Railways and roads were seriously underdeveloped at the time, so rivers were the only quick means of transportation, but with the current political atmosphere, this meant constant blockades, high tariffs, and even refusal of entry at times of high tension. Argentina was in constant turmoil. Civil wars sprung up periodically for decades as a clash between those who wanted independent states and those who wanted the central government in Buenos Aires to have more power. The Empire of Brazil, the most powerful country in the region, invaded Bolivia, then Peru invaded Bolivia. Then Peru and Bolivia invaded Chile. There was fighting and instability almost everywhere. Eventually, the border disputes had mostly been fought out and Argentina's civil wars resulted in a temporary victory for the central government. But, for the most part, Paraguay, despite being located in the center of the continent, had avoided much of this. Under the rule of a dictatorship, the country had declared itself an independent republic and adopted isolationism, focusing on becoming self-sufficient and building a strong military to enforce its borders and river entrances, and this was going quite well. Its economy was solid, it had an impressive army, and a huge fortress, but this era of isolation was about to end.\n\n## Uruguay as Catalyst: Colorados, Blancos, and the Road to War\n\nUruguay, or as it was known then, the Banda Oriental, was the smallest country in the story, but ultimately the catalyst for the entire conflict. After years of fighting with their neighbors, especially Brazil, Uruguay was finally recognized as independent at the end of the 1828 Cisplatine War. But Uruguay was still seen as a threat, and had to constantly defend itself from Argentina and Brazil, not to mention going through its own civil war, a clash between the conservative Blancos and the liberal Colorados. Eventually, the Blancos gained power, and surprisingly the two parties worked toward a \"fusionist\" government, based on compromises from both sides. Some progress was made in Uruguay's government for a couple of years, but in 1858 the Colorado party rejected the fusionist policy and began to rebel. The leaders of the rebellion were apprehended and executed, but this only fanned the flames of the movement, and soon the Colorado party was rising up, vowing to avenge the executed leaders that they saw as martyrs of their cause. The remaining government officials and military split between their alliances and Uruguay was once again thrown into political war. This time, things were going to escalate. The leader of the Colorado rebellion, Venancio Flores, approached Argentina and asked for support. Argentina agreed, as long as the Colorados would in turn support Argentina in their internal war with the federalist movement. With the Colorados at their side, in 1861 Argentina defeated the federalists, who retreated to a western province, and once again united the country under a central government in Buenos Aires. Then, just as promised, in 1863 Argentina began shipping weapons, ammunition, and volunteers to aid the Colorado insurgency in Uruguay, and the fighting against the government intensified. While this was all going down, Brazil was keeping a close eye on the hostilities in Uruguay, for several reasons. Brazil was highly invested in the Platine Basin and was hoping to take some of it from Uruguay. Nearly 20% of Uruguay spoke Portuguese at the time, and many of these people considered themselves Brazilian, not Uruguayan. Finally, Brazil needed an excuse to show their military might, because they were also on the verge of a possible war with the British Empire. When the Brazilian government was approached by the Colorados, they jumped at the possibility of installing a friendly government next door, and signed the alliance. Now faced with three enemies, the Uruguayan Blanco government was desperate for their own ally, and sent delegates to Paraguay. They had been trying to establish relations with Paraguay for years, but the dictator, Carlos Antonio López, was uninterested, and stayed true to his isolationism until his death in 1862. His son, Francisco Solano López, took his place as dictator, and saw the value in an alliance with Uruguay. His fear was that if Uruguay fell to the Colorado movement, Paraguay would be alone, surrounded by hostile countries, and could be crushed by them once they had straightened out their own problems. López vowed to protect the Blanco government, and with that promise, all the pieces were now in place for the Uruguayan War to evolve into something much bigger.\n\n## The Paraguayan Offensives: Striking Brazil and Argentina\n\nIn September of 1864, Brazil officially joined the fight in Uruguay, sending warships to \"protect Brazilian assets.\" Brazilian ground forces soon moved across the border and began besieging Uruguayan cities. Paraguay had been carefully watching these developments while drafting a considerable percentage of its population, and chose to strike while Brazil was distracted. In November 1864, the Paraguayan navy surrounded and seized the Brazilian steamboat Marquês de Olinda while it was sailing in the Paraguay River. This is widely regarded as the beginning of the Paraguayan War, a significant escalation from everyone just meddling in Uruguay's politics. The Marquês de Olinda was carrying supplies to their allies in Uruguay, and on board the boat was the recently appointed president of Mato Grosso, a province in western Brazil. All of the boat's passengers were imprisoned, and all but two died in the coming months behind bars. In late December 1864, with the help of information interrogated out of the captured passengers, Paraguay launched a ground invasion of Mato Grosso, Brazil. Two separate forces moved into Brazil on the same day. The first force, made up of 3,200 men, was moved across the Paraguayan River on boats and began assaulting the Nova Coimbra fort, which was guarded by 154 Brazilian soldiers. The defenders, impressively, held out for three whole days until they ran out of ammunition, at which point they rushed aboard a gunship and fled upstream. After the Paraguayan soldiers secured the fort, they continued marching northward, capturing the cities of Albuquerque, Tage, and Corumbá. The second strike force, made up of 4,650 men, landed at the same starting point but instead marched inland, deeper into Mato Grosso. After defeating the initial resistance, they began capturing settlements with ease, but stopped before marching into the province's capital, Melgaço, which was heavily fortified. Instead, they occupied the area's diamond and gold mines, sending the spoils back home to Paraguay. Brazil quickly mobilized forces and sent troops to recapture the lost territory, but it would take them almost a year to get there. They didn't encounter any trouble or delays along the way — they just had to walk 2,000 kilometers, or over 1,200 miles, across four Brazilian provinces. For reference, that is even longer than walking from Moscow to Berlin. Brazil is just that massive. Meanwhile, López was keeping a close eye on Argentina. Argentina was technically staying neutral in the hostilities between Paraguay and Brazil, but López didn't trust them. Despite their neutrality, they had repeatedly allowed Brazilian ships to sail up and down their rivers, delivering supplies and dropping off reinforcements. Paraguay, however, was denied such privilege when they asked Argentina to allow the transport of troops through their country. In March 1865, the Paraguayan Congress met in their capital, Asunción. After a week of debate, they voted to declare war on Argentina for its hostile policies, and López sent the declaration of war to Buenos Aires on March 29th. Two weeks later, the Paraguayan Navy sailed down the Paraná River and attacked Argentinian ships docked at the provincial capital city Corrientes. They quickly destroyed several ships and moved in with a force of 3,000 foot soldiers and 800 cavalry, capturing the city in a single day. López had hoped to gain the support of the city's Governor, who was known for his opposition to Argentina's government, but he refused. 1,500 soldiers were left to guard Corrientes, and the rest began marching southward deeper into Argentina along the banks of the Paraná River. Paraguay was off to an excellent start in the war, and wanted to capitalize on this momentum as soon as possible, so López opened another front in the fighting, sending 12,000 men into the Brazilian province of Rio Grande do Sul, where they successfully captured several cities over the next few weeks.\n\n## The Treaty of the Triple Alliance and the Battle of Riachuelo\n\nParaguay's momentum was about to all but disappear. López was unable to get his troops to Uruguay in time, and Colorado and Brazilian forces entered Uruguay's capital and dethroned the Blancos, killing off the opposition and removing anyone with any ties to the old government. With the Colorados now ruling the country, Uruguay had essentially switched sides in the conflict, and in May 1865, Uruguay, Argentina, and Brazil signed the Treaty of the Triple Alliance. The treaty consisted of 19 articles, each outlining how the alliance would act. Article 3 stated that Argentina was appointed the leader of the land forces, and Article 4 appointed Brazil the leader of the combined allied navies. But the most crucial point of the treaty was Article 6: \"The allies pledge themselves solemnly not to lay down their arms unless by common accord, nor until they have overthrown the present Government of Paraguay, nor to treat with the enemy separately, nor sign any Treaty of peace, truce, armistice, or Convention whatsoever for putting an end or suspending the war, unless by a perfect agreement of all.\" It was now three countries versus one, and there would be no end to the war until Paraguay had been completely eliminated. The next major encounter came just a month after the signing of the treaty. López knew that in order for Paraguay to emerge victorious over the Triple Alliance, he would need to control the rivers, so he armed his ships and set out for a surprise attack on the Imperial Brazilian Navy, the most powerful navy in South America. The Brazilian ships were gathered near the city of Corrientes, which was still occupied by Paraguay, so López concocted the perfect plan. As the sun set and the Brazilian sailors disembarked to sleep on the shore, his men would silently sail down the Paraguayan River, get as close as possible, and board the enemy ships before dawn, capturing them all without firing a shot. However, en route to Corrientes, one of the Paraguayan steam engines broke down. The fleet stopped for several hours while workers tried their best to fix the engine, but no one could start it back up. Finally, they gave up, the sailors transferred to other ships, and the fleet continued on its way. But this pitstop took away several hours of crucial nighttime from the Paraguayans, whose entire plan revolved around stealing the Brazilian ships under the cover of the dark, and by the time they arrived, the sun was already beginning to rise. By some monumental stroke of luck, a thick fog was covering the river and most of the Brazilian forces were still on land, meaning there was still a chance to continue with the original orders. But López was not there to lead his men; instead, he had placed the Paraguayan fleet under the command of Commodore Ignacio Meza, who decided to change the plans at the last minute. Meza ordered the ships to sail further downstream, where they would open fire on the Brazilian camps and docked ships, in coordination with their ground forces in the city. This was the Battle of the Riachuelo, and the first shot was fired at 9:25 AM on July 11, 1865. The Paraguayan fleet consisted of two corvettes, eight steamers, and seven barges, along with thousands of men on the shore joining the fight with 22 cannons. The fleet sailed in a line parallel to the docked Brazilian ships and fired every gun at their disposal. Under heavy fire, the Brazilians scrambled to get onto their ships as quickly as possible and began firing back. Two Paraguayan ships were damaged, so they moved downstream and dropped their anchors in a narrow part of the river, effectively trapping the Brazilian navy in its place. Brazilian Admiral Francisco Barroso realized what was happening and tried to reorganize his fleet by leading them downstream. However, one ship accidentally turned the wrong way, and most of the others mistakenly followed it. The Brazilian forces were now split into two separate groups, and the ship that caused the confusion accidentally ran aground and was destroyed soon after. Admiral Barroso, on board the steam frigate Amazonas, realized that he had to take a risk to save the battle, so he turned his ship around and headed straight for the Paraguayan gunships. The first ship he encountered was the fearsome Paraguarí, heavily armed with a hull made of metal. Barroso promptly rammed it, disabling it instantly. Then he continued, ramming three more ships in his path, putting two of them out of commission and outright sinking the third. The Paraguayans, realizing that the tide in the battle was quickly turning against them, began retreating back upstream, and their ground forces moved inland. The intense fighting had lasted six hours, during which time Paraguay suffered 750 casualties, lost four steamboats, and all seven barges. Ironically, one of the ships that had been rammed and sunk was the Marquês de Olinda, the steamboat that Paraguay stole from Brazil months earlier. Nearly every surviving ship had serious damage to it, and Commodore Meza had been killed from a bullet wound to the chest. Brazil, on the other hand, only lost one of their corvettes — the one that had beached itself during the fighting — and had around 200 casualties. It was a decisive naval victory, and Paraguay would now struggle to keep a military presence on the waters with its weakened navy.\n\n## The Battle of Tuyutí: The Bloodiest Day in South American History\n\nThings were looking grim on land as well. Just a couple of months later, part of Paraguay's forces that had entered Brazil earlier were still marching south into Uruguay, where they encountered a large Allied force, kicking off the Battle of Yatay. The Allies had strong numbers, with 5,500 infantry, 5,000 cavalry, and 32 cannons, heavily outnumbering the Paraguayans, who had only 2,000 infantry, 1,000 cavalry, and not a single cannon. The battlefield was, to say the least, miserable — the rivers nearby had recently flooded, turning the whole scene into a swampy, muddy mess. The first two hours of the battle were fought almost entirely by the cavalry, but once there was a break in the mounted combat, the Allied cannons had a chance to open fire, and a quick victory was achieved. Of the 3,200 Paraguayans in the battle, 1,700 were killed, and the rest were injured or taken prisoner. The Allies emerged with minimal casualties, only losing 150 men. The Battle of Yatay marked two consecutive decisive victories for the Allies, and López knew he was in trouble. He began consolidating his forces back home in Paraguay, preparing to defend his country. At the end of 1865, the Allies took the war to López himself and invaded Paraguay. Paraguayan defenses scored minor victories, but the overall attack was overwhelming, and the Allies were steadily gaining ground. It was clear to López that if the war continued in this fashion, Paraguay would slowly crumble under the pressure, so he launched a massive counterattack, the biggest battle of the war thus far. He planned to surprise the Allied armies that were camping at Tuyutí, a small corner of Paraguay described as a \"swampy, scrub-brush savannah.\" It was wet, disease-filled, and mosquito-ridden, but soon it would also be covered in blood and bullets. The Paraguayans marched from the north in four columns, numbering 26,000 men. The Allies were camped in the marsh, spread out in multiple groups. Argentina held the right flank, cavalry in the front and cannons in the back. A mixture of Brazilian and Uruguayan forces made up the center and the left flank, with cannons in several locations. The Allies numbered 35,000 soldiers, once again entering the battle with the numerical advantage, but López believed that the element of surprise would give his men a shot at victory. Originally, all four columns were to move into position around the swamp and attack at dawn, but getting into position took hours longer than expected, and finally, at noon, the signal was given for the battle to commence. Immediately after the signal was given, General Díaz charged forward with his cavalry, heading straight for Uruguayan cannons. As they got closer, they were torn apart by the entrenched Allies, who fired concentrated musket volleys and cannon fire on the horses as they charged, destroying half of the cavalry before the survivors turned back. After reorganizing, Paraguayan infantry marched to the Brazilian left flank but was once again stopped short, with musket rounds raining on them like hail as they trudged through the mud and grass. The cavalry regrouped and led yet another charge on the cannons, but this time were completely and utterly wiped out before even touching the Allied front line. Waves of Paraguayan infantry marched toward the left flank, with the piling bodies of their fallen comrades becoming yet another obstacle in the swamp. Eventually, they made it to the Allied trenches, and both sides continued ferociously firing on one another. One Brazilian general was shot off of his horse three separate times but each time managed to climb back on, and eventually went back to camp to treat his wounds. While the stubborn Allied frontline refused to give in, a regiment of Paraguayan cavalry rode far to the left of the Allied formation, using the thick trees as cover, and managed to circle around nearly to the back of the Allied forces. They inflicted heavy casualties and started gaining ground, but Brazilian reinforcements arrived and held them off. More Paraguayan infantry arrived to help the cavalry push through, and this only triggered more Allied groups to join the fight. Soon, intense gunfire was raging near the rear of the battlefield, with heavy losses piling up on either side. Just as it seemed like the Paraguayans would break through, the Uruguayan cannons arrived and put an end to their advance. On the right flank, the Paraguayan cavalry had made significant progress against the Argentinian infantry, breaking through their front line and attempting to surround and eliminate the Allied defenders. But the Argentinians held their ground bravely, forming tight groups of bayonets to keep the enemy horses at bay and firing when they had the chance. They held off the attackers just long enough for the Argentinian cannons to move into position, which started firing as quickly as possible. Before retreating, the cavalry tried one last charge but suffered heavy casualties and retreated back to the cover of the tree line. The fighting lasted only four hours, and by the end, the Allies had suffered 4,000 casualties. Paraguay's forces had been decimated: 6,000 of their men lay dead in the swamp, and another 7,000 were injured. Almost every single injured soldier died of infections in the coming days and weeks. There were so many bodies that the Allied soldiers simply piled them up in alternating stacks of wood and man, and burned them in mass pyres. The Battle of Tuyutí is still to this day the bloodiest individual battle in South American history. Tuyutí was also the last serious chance López had to defeat the Allies. He had lost not only thousands of his men but also his best leaders. He began filling his ranks with inexperienced conscripts, including children, slaves, and old men, who were carefully dressed to disguise their appearance in combat.\n\n## The Siege of Humaitá and the Fall of Asunción\n\nMeanwhile, diseases were spreading like a wildfire on both sides. At the Allied camp, 10,000 soldiers would die in the next few months from parasites, dysentery, and mosquito-borne diseases, and Paraguay was starting to suffer food shortages. After a failed peace meeting — where López offered to end the conflict and drastically reduce his nation's army, but the Allies refused anything short of removing him from power — the war continued. The Allies, furious and confident after their recent victories, stormed the Paraguayan defensive line at Curupayty in September 1866 with a renewed force of 20,000 men and 11 warships. What followed was the Allies' biggest defeat of the entire war. Brazilian ships opened the attack by coming close to shore and firing heavy guns at the defensive positions, with the aim to destroy Paraguayan cannons ahead of their ground forces. But despite firing 5,000 rounds, only one cannon of Paraguay's 49 was destroyed, and the Allied ground troops marched right into their path. Only 60 soldiers even made it to the fortress walls, who were quickly killed, and the rest were vaporized by orderly cannon fire. After just a few hours, the attack was abandoned, with the Allies suffering over 4,000 casualties, and the Paraguayans getting away with just 92 losses — an incredibly lopsided victory. The Allies' frustration with each other intensified, and their invasion of Paraguay was halted for a whole 10 months to rethink their plans, during which time cholera outbreaks ravaged the soldiers stationed around the besieged country. During these 10 months, the Allies worked to reform their armies. Brazil relieved most of its generals from duty and placed one man over all of their ground forces: Luís Alves de Lima e Silva, the Duke of Caxias, Marshal and Supreme Commander of the Imperial Brazilian Army. The 63-year-old Caxias put a serious effort into training his soldiers. He made sure everyone had better weapons, promoted the best officers, and, most importantly, improved the regiment's hygiene, effectively ending the outbreaks of disease that were so prevalent in the first years of the war. With his army now readier than ever, he looked for his next target. Entry into Paraguay on land would mean marching through more swamps, with extended supply lines and terrible conditions, but moving up the Paraguayan River would avoid all of this. Guarding the river, however, was the Fortress of Humaitá, \"a fortress the likes of which had never been seen in South America.\" It watched over a horseshoe bend in the Paraguayan River where the water narrowed to just a few hundred meters, meaning it effectively guarded all naval access to the country. Its artillery batteries stretched for nearly 2 kilometers along the river's coast, it could house 18,000 men, and was bristling with 150 cannons and hundreds of smaller mounted guns. To protect from cannon fire, its walls were several meters thick in some places. Certain bunkers could release torpedoes, which were essentially early forms of naval mines, into the narrow river. López, and all of Paraguay, were confident that it was indestructible. In fact, many historians believe that its strength caused López to act too boldly at the beginning of the war, knowing he could always fall back to his impenetrable defenses. Caxias decided that the best course of action was to surround the fortress and lay siege to it. The siege lasted for a grueling eight months. Humaitá finally fell in July 1868 when Brazilian ironclad warships successfully pushed past its defenses, cutting off its only remaining supply lines in the river. Brazil lost one of their ironclad warships to a torpedo and around 1,000 men throughout the conflict, and by that point, most of the Paraguayan forces had evacuated the fortress, sabotaging most of the equipment as they fled. The Allies now had undisputed access to the Paraguay River and turned their eyes to Paraguay's capital — Asunción. The Allied march to the capital was long and far from easy. All along the nearly 300-kilometer path, López sent forces to stop the Allies, but each time the Paraguayans were outmanned and outgunned, and suffered hundreds or thousands of losses. At the Battle of Avay, for example, Paraguayan troops ambushed Caxias but were unable to deal much damage and lost every one of their 3,600 men. By January 1869, Caxias and his men had arrived at Asunción and occupied the city within days. López fled to the mountains, refusing to surrender, and left his capital to be ransacked by the Allies. Soon there were 30,000 allied soldiers in the city, looting every market and house, and taking prisoners as they pleased.\n\n## The Death of López and the War's Devastating Legacy\n\nLópez began a long and brutal guerrilla war, recruiting nearly 10,000 men who carried out raids, ambushes, and attempted assassinations for months. In an effort to hunt López down and put an end to his movement, the Allies initiated the Campaign of the Hills — a force of 30,000 men who would move through the mountains and clear out any remaining resistance fighters. Finally, in March 1870, Brazilian soldiers surrounded López and his personal guard. He was given the option to surrender, but instead yelled, \"I die with my homeland!\" and charged with his sword. After a quick shootout, the dictator was dead. This marked the official end of the Paraguayan War, which lasted 5 years and 4 months. Brazil ended the conflict with an estimated 100,000 casualties, Argentina with an estimated 30,000, and Uruguay with at least 50,000. But the country that suffered the most in the end was Paraguay, with casualty estimates reaching as high as 400,000. The estimates vary, but a generally accepted figure is that Paraguay lost as much as 60% of its entire pre-war population. And because every man was forced to fight in the war, the country lost up to 90% of its male population, essentially leaving the vast majority of the country without fathers and husbands. If these numbers are even remotely accurate, it places the Paraguayan War as one of the most destructive wars for a single country in modern times. After the fighting ceased, the Triple Alliance also moved in to enact harsh punishments on Paraguay, through which Argentina and Brazil gained previously disputed parts of Paraguay's territory. As a result of the territorial changes, Paraguay lost nearly 40% of its claimed land and was also forced to pay war reparations, crippling its already destroyed economy. In the decades following the war, the remaining men were encouraged to have multiple wives in an attempt to repopulate the nation, supposedly even including Catholic priests, a culture which, according to some experts, still affects the country to this day. The Paraguayan War remains one of history's starkest reminders of the destruction of war and the dangers of a dictator.\n\n## Frequently Asked Questions\n\n### How did the Paraguayan War begin?\n\nThe war's immediate trigger was Paraguay's intervention in Uruguay's political crisis. Dictator Francisco Solano López had pledged to protect Uruguay's Blanco government, and when Brazil invaded Uruguay in September 1864 to install a friendly Colorado government, López responded by seizing a Brazilian steamboat, the Marquês de Olinda, in November 1864. He then launched ground invasions of Brazil's Mato Grosso province and, after Argentina refused passage to his troops, declared war on Argentina in March 1865 and seized the city of Corrientes.\n\n### What did the Treaty of the Triple Alliance commit its signatories to?\n\nSigned in May 1865 by Brazil, Argentina, and Uruguay, the treaty's most consequential provision was Article 6, which bound all three countries to fight until Paraguay's government was completely overthrown. The allies could not negotiate a separate peace, sign any truce, or lay down arms except by common agreement — meaning the war could only end with the removal of López from power.\n\n### What made the Battle of Tuyutí so devastating for Paraguay?\n\nAt Tuyutí in May 1866, López launched a surprise attack with four columns totaling 26,000 men against an Allied camp of 35,000 in a swampy savannah. The element of surprise was lost when the columns took hours longer than expected to reach position, and the Paraguayan attackers were torn apart by entrenched Allied cannons and musket volleys. In just four hours, Paraguay suffered 6,000 dead and 7,000 wounded — almost every injured soldier subsequently dying from infection — making it the bloodiest single battle in South American history.\n\n### How did the war finally end, and what were the consequences for Paraguay?\n\nBrazilian soldiers cornered López in March 1870 after years of guerrilla fighting through the mountains. Offered the chance to surrender, he charged with his sword and was killed in the ensuing shootout, officially ending the war after five years and four months. Paraguay lost an estimated 60% of its entire pre-war population and up to 90% of its male population. The country also lost nearly 40% of its territory to Argentina and Brazil and was forced to pay war reparations, crippling its already devastated economy.\n\n### What role did the Duke of Caxias play in breaking the stalemate?\n\nAfter the catastrophic Allied defeat at Curupayty — where over 4,000 Allied soldiers fell while Paraguay lost only 92 — Brazil relieved most of its generals and appointed Luís Alves de Lima e Silva, the Duke of Caxias, as supreme commander. The 63-year-old marshal retrained his troops, improved their weapons, promoted the best officers, and crucially improved camp hygiene to end the disease outbreaks that had decimated the Allied army. He then shifted the advance to the Paraguay River, laying siege to the formidable Fortress of Humaitá for eight months until it fell in July 1868, opening the path to Asunción.\n\n## Related Coverage\n- [Is the 21st Century's Deadliest War about to Restart? 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And More.](https://warfronts.pub/conflicts/is-russias-economy-starting-to-crack-and-more)\n\n" url: https://warfronts.pub/article/paraguayan-war-south-americas-most-devastating-conflict.md canonical: https://warfronts.pub/article/paraguayan-war-south-americas-most-devastating-conflict datePublished: 2026-03-04 dateModified: 2026-03-04 author: - name: Simon Whistler url: https://warfronts.pub/author/simon-whistler publisher: Warfronts image: "https://media.warfronts.pub/cdn-cgi/image/width=1600,height=900,fit=cover,quality=80,format=auto/articles/Eqr5DyCY0qQ/hero.jpg" type: NewsArticle contentHash: efe77a8d43b858831c05ea9a031b7141f497b5389ffa4ed6f43e577ca90712c5 tokens: 8227 summaryUrl: https://warfronts.pub/article/paraguayan-war-south-americas-most-devastating-conflict.md.summary.md --- Often overlooked in the history books, the Paraguayan War, also known as the War of the Triple Alliance, is a crucial piece of Latin American history. The war lasted more than five years, involved four separate countries, and was one of the deadliest conflicts of all time. The battles played out on both land and sea, and its bloody resolution helped shape South America as we know it today. What began as meddling in Uruguayan politics escalated into a war of annihilation that would claim as much as 60% of Paraguay's entire pre-war population and leave the country without fathers and husbands for a generation. ## Key Takeaways - Paraguay lost an estimated 60% of its entire pre-war population and up to 90% of its male population during the five-year conflict. - The Battle of Tuyutí remains the bloodiest single battle in South American history, with Paraguay suffering 6,000 dead and 7,000 wounded in just four hours. - The Treaty of the Triple Alliance's Article 6 bound Brazil, Argentina, and Uruguay to fight until Paraguay's government was completely overthrown. - Admiral Francisco Barroso turned the Battle of Riachuelo by personally ramming four Paraguayan ships with the steam frigate Amazonas, sinking or disabling them. - At Curupayty, the Allies suffered over 4,000 casualties while Paraguay lost only 92, the most lopsided battle of the war. ## A Continent in Turmoil: The Roots of Conflict The 19th century was a tumultuous time for Latin America. One after another, countries were slipping out of the control of their colonial powers, forging their own identities as independent nations. Now being able to govern themselves, and with Spain and Portugal no longer taking a hefty 20% tax on all goods, it seemed that each country had a chance to stand on its own two legs. But the colonial powers had left behind a bit of a mess in the continent when they left without marking clear borders between nations, and now every country had a territorial dispute with its neighbors. In some places, three countries all claimed the same piece of land, and they often fought over these. Railways and roads were seriously underdeveloped at the time, so rivers were the only quick means of transportation, but with the current political atmosphere, this meant constant blockades, high tariffs, and even refusal of entry at times of high tension. Argentina was in constant turmoil. Civil wars sprung up periodically for decades as a clash between those who wanted independent states and those who wanted the central government in Buenos Aires to have more power. The Empire of Brazil, the most powerful country in the region, invaded Bolivia, then Peru invaded Bolivia. Then Peru and Bolivia invaded Chile. There was fighting and instability almost everywhere. Eventually, the border disputes had mostly been fought out and Argentina's civil wars resulted in a temporary victory for the central government. But, for the most part, Paraguay, despite being located in the center of the continent, had avoided much of this. Under the rule of a dictatorship, the country had declared itself an independent republic and adopted isolationism, focusing on becoming self-sufficient and building a strong military to enforce its borders and river entrances, and this was going quite well. Its economy was solid, it had an impressive army, and a huge fortress, but this era of isolation was about to end. ## Uruguay as Catalyst: Colorados, Blancos, and the Road to War Uruguay, or as it was known then, the Banda Oriental, was the smallest country in the story, but ultimately the catalyst for the entire conflict. After years of fighting with their neighbors, especially Brazil, Uruguay was finally recognized as independent at the end of the 1828 Cisplatine War. But Uruguay was still seen as a threat, and had to constantly defend itself from Argentina and Brazil, not to mention going through its own civil war, a clash between the conservative Blancos and the liberal Colorados. Eventually, the Blancos gained power, and surprisingly the two parties worked toward a "fusionist" government, based on compromises from both sides. Some progress was made in Uruguay's government for a couple of years, but in 1858 the Colorado party rejected the fusionist policy and began to rebel. The leaders of the rebellion were apprehended and executed, but this only fanned the flames of the movement, and soon the Colorado party was rising up, vowing to avenge the executed leaders that they saw as martyrs of their cause. The remaining government officials and military split between their alliances and Uruguay was once again thrown into political war. This time, things were going to escalate. The leader of the Colorado rebellion, Venancio Flores, approached Argentina and asked for support. Argentina agreed, as long as the Colorados would in turn support Argentina in their internal war with the federalist movement. With the Colorados at their side, in 1861 Argentina defeated the federalists, who retreated to a western province, and once again united the country under a central government in Buenos Aires. Then, just as promised, in 1863 Argentina began shipping weapons, ammunition, and volunteers to aid the Colorado insurgency in Uruguay, and the fighting against the government intensified. While this was all going down, Brazil was keeping a close eye on the hostilities in Uruguay, for several reasons. Brazil was highly invested in the Platine Basin and was hoping to take some of it from Uruguay. Nearly 20% of Uruguay spoke Portuguese at the time, and many of these people considered themselves Brazilian, not Uruguayan. Finally, Brazil needed an excuse to show their military might, because they were also on the verge of a possible war with the British Empire. When the Brazilian government was approached by the Colorados, they jumped at the possibility of installing a friendly government next door, and signed the alliance. Now faced with three enemies, the Uruguayan Blanco government was desperate for their own ally, and sent delegates to Paraguay. They had been trying to establish relations with Paraguay for years, but the dictator, Carlos Antonio López, was uninterested, and stayed true to his isolationism until his death in 1862. His son, Francisco Solano López, took his place as dictator, and saw the value in an alliance with Uruguay. His fear was that if Uruguay fell to the Colorado movement, Paraguay would be alone, surrounded by hostile countries, and could be crushed by them once they had straightened out their own problems. López vowed to protect the Blanco government, and with that promise, all the pieces were now in place for the Uruguayan War to evolve into something much bigger. ## The Paraguayan Offensives: Striking Brazil and Argentina In September of 1864, Brazil officially joined the fight in Uruguay, sending warships to "protect Brazilian assets." Brazilian ground forces soon moved across the border and began besieging Uruguayan cities. Paraguay had been carefully watching these developments while drafting a considerable percentage of its population, and chose to strike while Brazil was distracted. In November 1864, the Paraguayan navy surrounded and seized the Brazilian steamboat Marquês de Olinda while it was sailing in the Paraguay River. This is widely regarded as the beginning of the Paraguayan War, a significant escalation from everyone just meddling in Uruguay's politics. The Marquês de Olinda was carrying supplies to their allies in Uruguay, and on board the boat was the recently appointed president of Mato Grosso, a province in western Brazil. All of the boat's passengers were imprisoned, and all but two died in the coming months behind bars. In late December 1864, with the help of information interrogated out of the captured passengers, Paraguay launched a ground invasion of Mato Grosso, Brazil. Two separate forces moved into Brazil on the same day. The first force, made up of 3,200 men, was moved across the Paraguayan River on boats and began assaulting the Nova Coimbra fort, which was guarded by 154 Brazilian soldiers. The defenders, impressively, held out for three whole days until they ran out of ammunition, at which point they rushed aboard a gunship and fled upstream. After the Paraguayan soldiers secured the fort, they continued marching northward, capturing the cities of Albuquerque, Tage, and Corumbá. The second strike force, made up of 4,650 men, landed at the same starting point but instead marched inland, deeper into Mato Grosso. After defeating the initial resistance, they began capturing settlements with ease, but stopped before marching into the province's capital, Melgaço, which was heavily fortified. Instead, they occupied the area's diamond and gold mines, sending the spoils back home to Paraguay. Brazil quickly mobilized forces and sent troops to recapture the lost territory, but it would take them almost a year to get there. They didn't encounter any trouble or delays along the way — they just had to walk 2,000 kilometers, or over 1,200 miles, across four Brazilian provinces. For reference, that is even longer than walking from Moscow to Berlin. Brazil is just that massive. Meanwhile, López was keeping a close eye on Argentina. Argentina was technically staying neutral in the hostilities between Paraguay and Brazil, but López didn't trust them. Despite their neutrality, they had repeatedly allowed Brazilian ships to sail up and down their rivers, delivering supplies and dropping off reinforcements. Paraguay, however, was denied such privilege when they asked Argentina to allow the transport of troops through their country. In March 1865, the Paraguayan Congress met in their capital, Asunción. After a week of debate, they voted to declare war on Argentina for its hostile policies, and López sent the declaration of war to Buenos Aires on March 29th. Two weeks later, the Paraguayan Navy sailed down the Paraná River and attacked Argentinian ships docked at the provincial capital city Corrientes. They quickly destroyed several ships and moved in with a force of 3,000 foot soldiers and 800 cavalry, capturing the city in a single day. López had hoped to gain the support of the city's Governor, who was known for his opposition to Argentina's government, but he refused. 1,500 soldiers were left to guard Corrientes, and the rest began marching southward deeper into Argentina along the banks of the Paraná River. Paraguay was off to an excellent start in the war, and wanted to capitalize on this momentum as soon as possible, so López opened another front in the fighting, sending 12,000 men into the Brazilian province of Rio Grande do Sul, where they successfully captured several cities over the next few weeks. ## The Treaty of the Triple Alliance and the Battle of Riachuelo Paraguay's momentum was about to all but disappear. López was unable to get his troops to Uruguay in time, and Colorado and Brazilian forces entered Uruguay's capital and dethroned the Blancos, killing off the opposition and removing anyone with any ties to the old government. With the Colorados now ruling the country, Uruguay had essentially switched sides in the conflict, and in May 1865, Uruguay, Argentina, and Brazil signed the Treaty of the Triple Alliance. The treaty consisted of 19 articles, each outlining how the alliance would act. Article 3 stated that Argentina was appointed the leader of the land forces, and Article 4 appointed Brazil the leader of the combined allied navies. But the most crucial point of the treaty was Article 6: "The allies pledge themselves solemnly not to lay down their arms unless by common accord, nor until they have overthrown the present Government of Paraguay, nor to treat with the enemy separately, nor sign any Treaty of peace, truce, armistice, or Convention whatsoever for putting an end or suspending the war, unless by a perfect agreement of all." It was now three countries versus one, and there would be no end to the war until Paraguay had been completely eliminated. The next major encounter came just a month after the signing of the treaty. López knew that in order for Paraguay to emerge victorious over the Triple Alliance, he would need to control the rivers, so he armed his ships and set out for a surprise attack on the Imperial Brazilian Navy, the most powerful navy in South America. The Brazilian ships were gathered near the city of Corrientes, which was still occupied by Paraguay, so López concocted the perfect plan. As the sun set and the Brazilian sailors disembarked to sleep on the shore, his men would silently sail down the Paraguayan River, get as close as possible, and board the enemy ships before dawn, capturing them all without firing a shot. However, en route to Corrientes, one of the Paraguayan steam engines broke down. The fleet stopped for several hours while workers tried their best to fix the engine, but no one could start it back up. Finally, they gave up, the sailors transferred to other ships, and the fleet continued on its way. But this pitstop took away several hours of crucial nighttime from the Paraguayans, whose entire plan revolved around stealing the Brazilian ships under the cover of the dark, and by the time they arrived, the sun was already beginning to rise. By some monumental stroke of luck, a thick fog was covering the river and most of the Brazilian forces were still on land, meaning there was still a chance to continue with the original orders. But López was not there to lead his men; instead, he had placed the Paraguayan fleet under the command of Commodore Ignacio Meza, who decided to change the plans at the last minute. Meza ordered the ships to sail further downstream, where they would open fire on the Brazilian camps and docked ships, in coordination with their ground forces in the city. This was the Battle of the Riachuelo, and the first shot was fired at 9:25 AM on July 11, 1865. The Paraguayan fleet consisted of two corvettes, eight steamers, and seven barges, along with thousands of men on the shore joining the fight with 22 cannons. The fleet sailed in a line parallel to the docked Brazilian ships and fired every gun at their disposal. Under heavy fire, the Brazilians scrambled to get onto their ships as quickly as possible and began firing back. Two Paraguayan ships were damaged, so they moved downstream and dropped their anchors in a narrow part of the river, effectively trapping the Brazilian navy in its place. Brazilian Admiral Francisco Barroso realized what was happening and tried to reorganize his fleet by leading them downstream. However, one ship accidentally turned the wrong way, and most of the others mistakenly followed it. The Brazilian forces were now split into two separate groups, and the ship that caused the confusion accidentally ran aground and was destroyed soon after. Admiral Barroso, on board the steam frigate Amazonas, realized that he had to take a risk to save the battle, so he turned his ship around and headed straight for the Paraguayan gunships. The first ship he encountered was the fearsome Paraguarí, heavily armed with a hull made of metal. Barroso promptly rammed it, disabling it instantly. Then he continued, ramming three more ships in his path, putting two of them out of commission and outright sinking the third. The Paraguayans, realizing that the tide in the battle was quickly turning against them, began retreating back upstream, and their ground forces moved inland. The intense fighting had lasted six hours, during which time Paraguay suffered 750 casualties, lost four steamboats, and all seven barges. Ironically, one of the ships that had been rammed and sunk was the Marquês de Olinda, the steamboat that Paraguay stole from Brazil months earlier. Nearly every surviving ship had serious damage to it, and Commodore Meza had been killed from a bullet wound to the chest. Brazil, on the other hand, only lost one of their corvettes — the one that had beached itself during the fighting — and had around 200 casualties. It was a decisive naval victory, and Paraguay would now struggle to keep a military presence on the waters with its weakened navy. ## The Battle of Tuyutí: The Bloodiest Day in South American History Things were looking grim on land as well. Just a couple of months later, part of Paraguay's forces that had entered Brazil earlier were still marching south into Uruguay, where they encountered a large Allied force, kicking off the Battle of Yatay. The Allies had strong numbers, with 5,500 infantry, 5,000 cavalry, and 32 cannons, heavily outnumbering the Paraguayans, who had only 2,000 infantry, 1,000 cavalry, and not a single cannon. The battlefield was, to say the least, miserable — the rivers nearby had recently flooded, turning the whole scene into a swampy, muddy mess. The first two hours of the battle were fought almost entirely by the cavalry, but once there was a break in the mounted combat, the Allied cannons had a chance to open fire, and a quick victory was achieved. Of the 3,200 Paraguayans in the battle, 1,700 were killed, and the rest were injured or taken prisoner. The Allies emerged with minimal casualties, only losing 150 men. The Battle of Yatay marked two consecutive decisive victories for the Allies, and López knew he was in trouble. He began consolidating his forces back home in Paraguay, preparing to defend his country. At the end of 1865, the Allies took the war to López himself and invaded Paraguay. Paraguayan defenses scored minor victories, but the overall attack was overwhelming, and the Allies were steadily gaining ground. It was clear to López that if the war continued in this fashion, Paraguay would slowly crumble under the pressure, so he launched a massive counterattack, the biggest battle of the war thus far. He planned to surprise the Allied armies that were camping at Tuyutí, a small corner of Paraguay described as a "swampy, scrub-brush savannah." It was wet, disease-filled, and mosquito-ridden, but soon it would also be covered in blood and bullets. The Paraguayans marched from the north in four columns, numbering 26,000 men. The Allies were camped in the marsh, spread out in multiple groups. Argentina held the right flank, cavalry in the front and cannons in the back. A mixture of Brazilian and Uruguayan forces made up the center and the left flank, with cannons in several locations. The Allies numbered 35,000 soldiers, once again entering the battle with the numerical advantage, but López believed that the element of surprise would give his men a shot at victory. Originally, all four columns were to move into position around the swamp and attack at dawn, but getting into position took hours longer than expected, and finally, at noon, the signal was given for the battle to commence. Immediately after the signal was given, General Díaz charged forward with his cavalry, heading straight for Uruguayan cannons. As they got closer, they were torn apart by the entrenched Allies, who fired concentrated musket volleys and cannon fire on the horses as they charged, destroying half of the cavalry before the survivors turned back. After reorganizing, Paraguayan infantry marched to the Brazilian left flank but was once again stopped short, with musket rounds raining on them like hail as they trudged through the mud and grass. The cavalry regrouped and led yet another charge on the cannons, but this time were completely and utterly wiped out before even touching the Allied front line. Waves of Paraguayan infantry marched toward the left flank, with the piling bodies of their fallen comrades becoming yet another obstacle in the swamp. Eventually, they made it to the Allied trenches, and both sides continued ferociously firing on one another. One Brazilian general was shot off of his horse three separate times but each time managed to climb back on, and eventually went back to camp to treat his wounds. While the stubborn Allied frontline refused to give in, a regiment of Paraguayan cavalry rode far to the left of the Allied formation, using the thick trees as cover, and managed to circle around nearly to the back of the Allied forces. They inflicted heavy casualties and started gaining ground, but Brazilian reinforcements arrived and held them off. More Paraguayan infantry arrived to help the cavalry push through, and this only triggered more Allied groups to join the fight. Soon, intense gunfire was raging near the rear of the battlefield, with heavy losses piling up on either side. Just as it seemed like the Paraguayans would break through, the Uruguayan cannons arrived and put an end to their advance. On the right flank, the Paraguayan cavalry had made significant progress against the Argentinian infantry, breaking through their front line and attempting to surround and eliminate the Allied defenders. But the Argentinians held their ground bravely, forming tight groups of bayonets to keep the enemy horses at bay and firing when they had the chance. They held off the attackers just long enough for the Argentinian cannons to move into position, which started firing as quickly as possible. Before retreating, the cavalry tried one last charge but suffered heavy casualties and retreated back to the cover of the tree line. The fighting lasted only four hours, and by the end, the Allies had suffered 4,000 casualties. Paraguay's forces had been decimated: 6,000 of their men lay dead in the swamp, and another 7,000 were injured. Almost every single injured soldier died of infections in the coming days and weeks. There were so many bodies that the Allied soldiers simply piled them up in alternating stacks of wood and man, and burned them in mass pyres. The Battle of Tuyutí is still to this day the bloodiest individual battle in South American history. Tuyutí was also the last serious chance López had to defeat the Allies. He had lost not only thousands of his men but also his best leaders. He began filling his ranks with inexperienced conscripts, including children, slaves, and old men, who were carefully dressed to disguise their appearance in combat. ## The Siege of Humaitá and the Fall of Asunción Meanwhile, diseases were spreading like a wildfire on both sides. At the Allied camp, 10,000 soldiers would die in the next few months from parasites, dysentery, and mosquito-borne diseases, and Paraguay was starting to suffer food shortages. After a failed peace meeting — where López offered to end the conflict and drastically reduce his nation's army, but the Allies refused anything short of removing him from power — the war continued. The Allies, furious and confident after their recent victories, stormed the Paraguayan defensive line at Curupayty in September 1866 with a renewed force of 20,000 men and 11 warships. What followed was the Allies' biggest defeat of the entire war. Brazilian ships opened the attack by coming close to shore and firing heavy guns at the defensive positions, with the aim to destroy Paraguayan cannons ahead of their ground forces. But despite firing 5,000 rounds, only one cannon of Paraguay's 49 was destroyed, and the Allied ground troops marched right into their path. Only 60 soldiers even made it to the fortress walls, who were quickly killed, and the rest were vaporized by orderly cannon fire. After just a few hours, the attack was abandoned, with the Allies suffering over 4,000 casualties, and the Paraguayans getting away with just 92 losses — an incredibly lopsided victory. The Allies' frustration with each other intensified, and their invasion of Paraguay was halted for a whole 10 months to rethink their plans, during which time cholera outbreaks ravaged the soldiers stationed around the besieged country. During these 10 months, the Allies worked to reform their armies. Brazil relieved most of its generals from duty and placed one man over all of their ground forces: Luís Alves de Lima e Silva, the Duke of Caxias, Marshal and Supreme Commander of the Imperial Brazilian Army. The 63-year-old Caxias put a serious effort into training his soldiers. He made sure everyone had better weapons, promoted the best officers, and, most importantly, improved the regiment's hygiene, effectively ending the outbreaks of disease that were so prevalent in the first years of the war. With his army now readier than ever, he looked for his next target. Entry into Paraguay on land would mean marching through more swamps, with extended supply lines and terrible conditions, but moving up the Paraguayan River would avoid all of this. Guarding the river, however, was the Fortress of Humaitá, "a fortress the likes of which had never been seen in South America." It watched over a horseshoe bend in the Paraguayan River where the water narrowed to just a few hundred meters, meaning it effectively guarded all naval access to the country. Its artillery batteries stretched for nearly 2 kilometers along the river's coast, it could house 18,000 men, and was bristling with 150 cannons and hundreds of smaller mounted guns. To protect from cannon fire, its walls were several meters thick in some places. Certain bunkers could release torpedoes, which were essentially early forms of naval mines, into the narrow river. López, and all of Paraguay, were confident that it was indestructible. In fact, many historians believe that its strength caused López to act too boldly at the beginning of the war, knowing he could always fall back to his impenetrable defenses. Caxias decided that the best course of action was to surround the fortress and lay siege to it. The siege lasted for a grueling eight months. Humaitá finally fell in July 1868 when Brazilian ironclad warships successfully pushed past its defenses, cutting off its only remaining supply lines in the river. Brazil lost one of their ironclad warships to a torpedo and around 1,000 men throughout the conflict, and by that point, most of the Paraguayan forces had evacuated the fortress, sabotaging most of the equipment as they fled. The Allies now had undisputed access to the Paraguay River and turned their eyes to Paraguay's capital — Asunción. The Allied march to the capital was long and far from easy. All along the nearly 300-kilometer path, López sent forces to stop the Allies, but each time the Paraguayans were outmanned and outgunned, and suffered hundreds or thousands of losses. At the Battle of Avay, for example, Paraguayan troops ambushed Caxias but were unable to deal much damage and lost every one of their 3,600 men. By January 1869, Caxias and his men had arrived at Asunción and occupied the city within days. López fled to the mountains, refusing to surrender, and left his capital to be ransacked by the Allies. Soon there were 30,000 allied soldiers in the city, looting every market and house, and taking prisoners as they pleased. ## The Death of López and the War's Devastating Legacy López began a long and brutal guerrilla war, recruiting nearly 10,000 men who carried out raids, ambushes, and attempted assassinations for months. In an effort to hunt López down and put an end to his movement, the Allies initiated the Campaign of the Hills — a force of 30,000 men who would move through the mountains and clear out any remaining resistance fighters. Finally, in March 1870, Brazilian soldiers surrounded López and his personal guard. He was given the option to surrender, but instead yelled, "I die with my homeland!" and charged with his sword. After a quick shootout, the dictator was dead. This marked the official end of the Paraguayan War, which lasted 5 years and 4 months. Brazil ended the conflict with an estimated 100,000 casualties, Argentina with an estimated 30,000, and Uruguay with at least 50,000. But the country that suffered the most in the end was Paraguay, with casualty estimates reaching as high as 400,000. The estimates vary, but a generally accepted figure is that Paraguay lost as much as 60% of its entire pre-war population. And because every man was forced to fight in the war, the country lost up to 90% of its male population, essentially leaving the vast majority of the country without fathers and husbands. If these numbers are even remotely accurate, it places the Paraguayan War as one of the most destructive wars for a single country in modern times. After the fighting ceased, the Triple Alliance also moved in to enact harsh punishments on Paraguay, through which Argentina and Brazil gained previously disputed parts of Paraguay's territory. As a result of the territorial changes, Paraguay lost nearly 40% of its claimed land and was also forced to pay war reparations, crippling its already destroyed economy. In the decades following the war, the remaining men were encouraged to have multiple wives in an attempt to repopulate the nation, supposedly even including Catholic priests, a culture which, according to some experts, still affects the country to this day. The Paraguayan War remains one of history's starkest reminders of the destruction of war and the dangers of a dictator. ## Frequently Asked Questions ### How did the Paraguayan War begin? The war's immediate trigger was Paraguay's intervention in Uruguay's political crisis. Dictator Francisco Solano López had pledged to protect Uruguay's Blanco government, and when Brazil invaded Uruguay in September 1864 to install a friendly Colorado government, López responded by seizing a Brazilian steamboat, the Marquês de Olinda, in November 1864. He then launched ground invasions of Brazil's Mato Grosso province and, after Argentina refused passage to his troops, declared war on Argentina in March 1865 and seized the city of Corrientes. ### What did the Treaty of the Triple Alliance commit its signatories to? Signed in May 1865 by Brazil, Argentina, and Uruguay, the treaty's most consequential provision was Article 6, which bound all three countries to fight until Paraguay's government was completely overthrown. The allies could not negotiate a separate peace, sign any truce, or lay down arms except by common agreement — meaning the war could only end with the removal of López from power. ### What made the Battle of Tuyutí so devastating for Paraguay? At Tuyutí in May 1866, López launched a surprise attack with four columns totaling 26,000 men against an Allied camp of 35,000 in a swampy savannah. The element of surprise was lost when the columns took hours longer than expected to reach position, and the Paraguayan attackers were torn apart by entrenched Allied cannons and musket volleys. In just four hours, Paraguay suffered 6,000 dead and 7,000 wounded — almost every injured soldier subsequently dying from infection — making it the bloodiest single battle in South American history. ### How did the war finally end, and what were the consequences for Paraguay? Brazilian soldiers cornered López in March 1870 after years of guerrilla fighting through the mountains. Offered the chance to surrender, he charged with his sword and was killed in the ensuing shootout, officially ending the war after five years and four months. Paraguay lost an estimated 60% of its entire pre-war population and up to 90% of its male population. The country also lost nearly 40% of its territory to Argentina and Brazil and was forced to pay war reparations, crippling its already devastated economy. ### What role did the Duke of Caxias play in breaking the stalemate? After the catastrophic Allied defeat at Curupayty — where over 4,000 Allied soldiers fell while Paraguay lost only 92 — Brazil relieved most of its generals and appointed Luís Alves de Lima e Silva, the Duke of Caxias, as supreme commander. The 63-year-old marshal retrained his troops, improved their weapons, promoted the best officers, and crucially improved camp hygiene to end the disease outbreaks that had decimated the Allied army. He then shifted the advance to the Paraguay River, laying siege to the formidable Fortress of Humaitá for eight months until it fell in July 1868, opening the path to Asunción. ## Related Coverage - [Is the 21st Century's Deadliest War about to Restart? 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