"Imperialism" is a very broad concept, and requires clarifications.
If you meen British imperialism, that is, the interpretation according to which the Paraguayan war was caused, ultimately, because the main industrial world power, the UK, couldn't allow the existance in South America of a country that seeked to have its own industry and didn't imported British manufactured goods, you must know thisinterpretation has been seriously questioned by serious historians, like Brazilian Doratioto. It implies that Argentina, Brazil and Uruguay are mere brazilian puppets, which wasn't the case: in fact, relations between Brazil and Paraguay weren't going well back then. It also implies that Paraguay was on the path of becoming and industrial powerhouse, which is also debatable (obviuously, it was far better before the war than afterwards, but how better and how sustainable its model was is debetable).
They would get a common enemy in Argentina, but I'm not sure Chile would want a war with Argentina by the 1860s or 70s. The territorial dispute was regarding Patagonia, which was unsettled then. If Argentina was to involve in a long and costly war against Paraguay and Brazil, Chile could snatch the regions of Patagonia east of the Andes (or the entire Tierra del Fuego island) while Argentina was otherwise occupied, and thus Chile would avoid a direct confrontation.The notion that Paraguay and Brazil would align with Chile needs some explanation. Why?
They would get a common enemy in Argentina, but I'm not sure Chile would want a war with Argentina by the 1860s or 70s. The territorial dispute was regarding Patagonia, which was unsettled then. If Argentina was to involve in a long and costly war against Paraguay and Brazil, Chile could snatch the regions of Patagonia east of the Andes (or the entire Tierra del Fuego island) while Argentina was otherwise occupied, and thus Chile would avoid a direct confrontation.
The catch during the Pacific War is, the Argentine leadership didn't want nor needed a war with Chile. Of course, with a POD in which the proper idiots end up in charge, it might happen. I think you'll need to butterfly Julio Roca for that: the man didn't like to start wars if the enemy was white.Argentina can join the Peru-Bolivian aliance against Chile: Bolivia and Peru can keep their territories in the north, and Argentina can get all Patagonia. Brazil will support Chile for avoid a powerful Argentina. Paraguay will ally to Brazil for be against Bolivia in the issue of Chaco. Result: the Sudamerican War.![]()