The Naval Battle of the Riachuelo took place in the context of the Paraguayan War, a conflict that erupted in the 1860s involving Paraguay against the Triple Alliance of Brazil, Argentina, and Uruguay. The battle occurred on the Riachuelo rivulet, where the Brazilian Navy sought to eliminate the Paraguayan naval threat and ensure control over the critical waterways. The Paraguayan Navy, under Captain Pedro Ignacio Multedo, was primarily composed of small vessels, which were at a disadvantage compared to the more advanced Brazilian fleet led by Admiral Francisco Manuel Barroso da Silva.

As the two fleets clashed, the Brazilian Navy employed superior tactics and weaponry that allowed them to inflict significant damage on the Paraguayan ships. The battle was not only a show of naval strength but also an important morale booster for the Brazilian forces and their allies. The victory at the Riachuelo effectively neutralized Paraguayan naval operations and enabled the Triple Alliance to gain a foothold in the war, ultimately leading to increased cooperation among Brazil, Argentina, and Uruguay against a common foe.

Following the battle, the ramifications were felt throughout the conflict, as the Brazilian victory contributed to a shift in power dynamics in the region. The inability of Paraguay to maintain control over its waterways severely hampered its ability to transport troops and supplies, which was critical for its military campaigns. This victory laid the groundwork for subsequent operations by the Triple Alliance forces and marked a turning point in the Paraguayan War, influencing its direction and eventual outcome.