Barroso bombarded Paraguayan fortifications in 1866 and 1867 a number of times before she participated in the Passagem de Humaitá in February 1868.

Barroso was designed to meet the need of the Brazilian Navy for a small, simple, shallow-draft armored ship capable of withstanding heavy fire.

The engine produced a total of 420 indicated horsepower (310 kW) which gave the ship a maximum speed of 9 knots (17 km/h; 10 mph).

The casemate was protected by 102 millimetres of armour on all four sides, backed by 609 millimeters (24.0 in) of wood capped with a 102 mm layer of peroba hardwood.

The ship bombarded Curuzu Fort, downstream of Curupaity, on 1 September in company with the ironclads Rio de Janeiro, Brasil, Lima Barros, Tamandaré, and the monitor Bahia.

[5] On 22 September the Allied army attempted to storm the fortifications at Curupaity, supported by fire from the Brazilian ironclads, but was rebuffed with heavy losses.

[5] The Brazilians broke through the river defences at Curupaity during daylight on 15 August 1867 with Barroso, Tamanadaré, and eight other ironclads.

[7] On 19 February 1868 six Brazilian ironclads, including Barroso, steamed past Humaitá at night.

Three Pará-class river monitors, Rio Grande, Alagoas and Pará were lashed to the larger ironclads in case any engines were disabled by the Paraguayan guns.

On 23 March Rio Grande and Barroso sank the steamer Igurey and both ships were boarded by Paraguayan soldiers on the evening of 9 July, although they managed to repel the boarders.