War of the Triple Alliance (1864-1870), also called the Paraguayan War, was the bloodiest war in Latin American history. The conflict pitted Paraguay against the nearby nations of Argentina, Brazil, and Uruguay, known as the Triple Alliance. Paraguay lost the war, its population was devastated, and much of the country was destroyed.
In 1862, Paraguay’s first president, Carlos Antonio López, died after 21 years in power. His son, Francisco Solano López, took over the country as president with dictatorial powers. Francisco believed that Argentina and Brazil wished to occupy Paraguay and Uruguay, so he signed a defense treaty with Uruguay. In 1864, Paraguay went to war against Brazil to defend Uruguay’s government. After Argentina refused to let Paraguayan troops cross its territory to attack Brazil, López declared war on Argentina as well. In 1865, Brazil helped a new government take hold in Uruguay, which joined with Argentina and Brazil to form the Triple Alliance against Paraguay.
After initial Paraguayan victories, the turning point of the war came at the 1866 Battle of Tuyutí in southwestern Paraguay. In the bloodiest battle ever in South America, some 17,000 soldiers were killed at Tuyutí—most of them Paraguayan. A series of desperate battles followed as the Alliance armies gained the upper hand. By January 1869, Alliance troops had captured Asunción, the Paraguayan capital, and controlled much of Paraguay. But López and a stalwart group of soldiers continued fighting a guerrilla campaign in the mountains. Guerrilla warfare is conducted by roving bands of fighters who stage ambushes, sudden raids, and other small-scale attacks. Brazilian troops eventually caught up with López and his remaining forces in the Cerro Corá valley of northeastern Paraguay. On March 1, 1870, the Brazilians killed López, marking the end of the war.
The war left Paraguay in ruins. The country lost a significant portion of its population to battles, disease, and famine. Some historians estimate that more than half of the population died. In total, as many as 400,000 people died in the conflict. Paraguay also lost a fourth of its territory. After the war, power struggles among rival political groups plagued the country. More than 30 presidents headed Paraguay’s government from 1870 to 1932.