In 1865, Francisco Solano Lopez's armies and navies were on the offensive. Three nations joined the war against Paraguay: Brazil, Argentina, and Uruguay, a combination that came to be known as the Triple Alliance. Alliances have their problems, but Paraguay was fighting all alone...and as it turned out, that was worse.
Especially when they had to fight naval battles with canoes.
Maps: https://www.unknownsoldierspodcast.com/post/paraguayan-war-part-2-the-triple-alliance-maps
Audible Recommendation: https://www.audible.com/pd/To-Rule-the-Waves-Audiobook/B01MRXZIE1?action_code=ASSGB149080119000H&share_location=pdp
Music: "Down the River" by lynnepublishing, via Pond5.com: https://www.pond5.com/royalty-free-music/item/47771833-down-river-loop-01