In 1864, Paraguay fought the War of the Triple Alliance against Brazil, Argentina and Uruguay. Paraguay lost in devastating fashion, crippling the country. What caused this war and why did Paraguay fight against an alliance of clearly stronger foes?

Sorry for this super late response but here I go:

Winning a war against the Brazilian Empire alone was possible since it's army wasn't well organized yet and Paraguay well developed technologically. Not sure about Argentina.

As for the causes of the war.

Short version: -Territorial disputes left unfinished by Carlos Antonio López before his son became the ruler. -Francisco Solano López having aggresive policies. -Bad relations with Argentina and the Brazilian Empire. -Desperate attempts to support the Uruguayan government.

Long version: There was a civil war going in Uruguay before the Triple Alliance War. Francisco Solano López believed the access of the Paraguayan merchant fleet depended on the positive relations with the Uruguayan Government. This is because the Argentine government refused to recognize Paraguay's independence and instead claimed it as a province of Argentina.

Here is when things start to get nasty, the Brazilian Empire supported the rebels, López threatened Brazil to declare war if it refused to remain neutral. Brazil kept supporting the rebels, thus López invaded Matto Grosso, the war starts.

López tried marching his army through Argentine territory to support the Uruguayan Government, Argentina denied the pass and López declared war on Argentina as well. (Why López didn't transport his troops through the Paraguay River is beyond me).

The Rebel faction in Uruguay won the civil war and Uruguay signed the Treaty of the Triple Alliance with the Brazilian Empire and Argentina in wich it was established that the territories would be reparted between Brazil and Argentina. Uruguay got no territories from Paraguay.

There is also a majorly spread theory across Paraguay that the war orchestrated by the United Kingdom to crush Paraguay because it's economy was thriving and could soon become some international power and rival. But there is not enough evidence to back this up.

/r/AskHistorians Thread