It included the Pará-class monitors Alagoas and Rio Grande, as well as some smaller wooden ships.

In 1872, however, Estanisláo Przewodowski, a native of Bahia and of Polish origin, was appointed commander of the flotilla.

[1] In 1874, Pamphilo Manoel Freire de Carvalho, a medical lieutenant-captain who had come to the aid of a wounded Brazilian in the nearby Argentine town of Itaqui de Alvear, was assaulted by two healers of Italian origin in front of the local police, who did not react.

[2] Przewodowski, in reaction, repeatedly asked the Argentine authorities to hand over the aggressors.

Seeing no reaction, he ordered on June 22 that both flotilla monitors execute hourly bombardments against the city's outposts, until, at the fourth firing, a committee of Alvear residents went to Itaqui to negotiate a ceasefire, which Przewodowski granted.