Amid escalating diplomatic tensions in South America, José Antônio Saraiva, then the Minister of War for Brazil, announced military reprisals against Uruguay on October 8, 1864. This decision came in response to the Blanco Party's refusal to meet Brazil's demands regarding various political and economic issues affecting Brazilian nationals and interests in Uruguay. At the core of this conflict was Brazil’s desire to exert greater control over its neighbor and ensure the protection of its citizens and commerce. The refusal of the Uruguayan government led Brazil to mobilize its military forces, signaling a decisive shift from diplomatic pressure to direct military action.

The Brazilian military then began operations aimed at destabilizing the Blanco governorship by supporting opposition factions within Uruguay. This military action laid the groundwork for a wider conflict known as the Uruguayan War, which would draw in regional powers like Argentina and have long-lasting implications for the political landscape of South America. The subsequent declarations of war and the mobilization of troops led to armed confrontations that significantly altered alliances and power balances within the region.

In the months that followed, incidents along the borders escalated, leading to intense fighting between Brazilian and Uruguayan forces. The conflict reflected the broader geopolitical struggles of the time, wherein nations in Latin America sought to navigate their sovereignty against influential neighbors. In doing so, it marked a significant moment of militarization that changed the dynamics of regional politics, as Brazil aimed to solidify its standing as a leading south American power.