Based on the critic to the hegemonic historiography interpretations of the War of the Triple Alliance (1865-1870), this article proposes to insist on another approach to the event which should be transversal to the States (Argentina, Brazil, Paraguay and Uruguay). Article argues that the “general” interests of the young nations cannot explain the emergence of the conflict; rather, the local classes' forms of response to the advance of the contemporary International Labour Division - emerged by British impulse to free trade after the repeal of the corn laws (agricultural protectionist laws) - are the key to comprehend those facts. To arrive to the objective of rethinking the question on new coordinates, the article is presented with an introduction to the topic, continues with the analysis in each social formation and exposes the competent reflections.