The navy had great difficulties with this ship, which was hard to navigate and, due to the design of its casemate, which left a part of it unprotected, it was vulnerable to diving projectiles.

In 1873, it was assigned to the third naval division, with the mission of patrolling the Brazilian coast between Mossoró, in Rio Grande do Norte, and the border with French Guiana.

Added to this was the fact that the ship was built with a system of double casemates that left, amidships, an unprotected area over the boilers, vulnerable to diving shots.

[4] This fleet bombed the fortress together with the battery from the Curuzú fortress [pt], already taken by the Brazilians, with the soldiers of the 48th Battalion of Fatherland Volunteers and with the fleet of chief Elisiário dos Santos [pt], which included the Araguari and Iguatemi gunboats, the steamer Lindóia, the bomber Pedro Afonso, the barge Mercedes and the launch João das Botas.

[c] According to a Brazilian historian:[9] "Curupayty resisted with all the powers of despair, filling the air with a hideous roar, and not being able to hold back with strings of bullets the gallant ships that followed their destiny.

The ships Cabral, Brasil, the monitor Lima Barros and seven other battleships from the fleet that had bombed the fortress on 2 February took about two hours to complete the crossing.

For six months, the ships remained in this position, carrying out actions against the fortress of Humaitá and supporting the monitors who forced the passage of the fort on February 19th.

The distance from the fortification allowed the ships to be protected from their guns, but three pieces of Paraguayan artillery, installed in a wood close to the battleships, often attacked them.

Roque da Silva noticed an unusual movement of water hyacinths descending the river and, as he approached, he saw that they were in fact Paraguayan canoes full of armed men.

The assailants were armed with sabers, pistols, axes and machetes, as well as hand grenades and rockets that they planned to launch inside the ships.

On the contrary, the Paraguayans began to attack with redoubled fury, desperately trying to open ruptures in the ship with axes to launch their hand grenades.

[12] On April 10, Cabral and the fleet of its division (Alvim) began a long bombardment of the fortress of Humaitá, in preparation for the attack by the Allied army under the command of the general Marquis of Caxias, which took place on July 16.

[16] Still on 21 July, the squadron left from Araçá island and headed towards a position of Paraguayan batteries below the Arroio Guaicuru, which constantly threatened army troops stationed in the Chaco.

On the same day, the squadron, made up of the battleships Bahia and Silvado and the monitors Alagoas and Piauí, under the command of chief Delfim Carlos de Carvalho, was ordered to position itself near the Timbó fort.

[17] That night, the battleships and monitors challenged Timbó's batteries, positioned so that they could efficiently hit a wide stretch of the river, and successfully dashed past the fortress.

[18] On 16 August, Cabral, Brasil and Tamandaré, a squadron under the command of the Viscount of Inhaúma, left from Humaitá and received orders to also force the passage of Timbó.

[17][18][19][20] During October 1868, the battleships Tamandaré, Bahia, Silvado, Barroso, Colombo, Brazil, Alagoas, Lima Barros and Rio Grande do Norte, in that order, forced the passage of Angostura, a fortress on the Paraguay River heavily defended by batteries.

On 19 November, the fort was again violently bombarded by the same squadron, with the support of Herval and Mariz e Barros, with captain Mamede Simões directing the action.

[19][22] After the conquest of Asunción, on 1 January 1869, the already worn out large battleships, such as Cabral, were no longer as useful in the conflict, with naval combats taking place, from then on, in small, very narrow streams.

[23] In the first district, which ran from the extreme south of the country to the border between the provinces of Rio de Janeiro and Espírito Santo, the battleships Brasil, Lima Barros, Silvado and Bahia were allocated.

On 24 July 1878, the imperial navy issued an unfavorable opinion to the request of Cabral's officers to include the time of service they provided on board the ship when it was designated as a river battery, since 12 May 1876, due to bad navigation conditions.

The command of the second naval district communicated, on 9 November 1882, that on the 8th, Cabral had been disarmed and its hull had been handed over to the Bahia Arsenal, thus ending its activities.