From 1864 to 1870, Brazil, Argentina and Uruguay (the "Triple Alliance") were at war with neighboring Paraguay to form the "Paraguayan War". Such a conflict required modern means with which to wage war and this prompted Brazil to commission a new shallow-draught armored ironclad named after Admiral Fancisco Manoel Barroso de Silva (1804-1882). Construction of the "Barroso" began on February 21st, 1865 under the direction of the Arsenal de Marinha da Corte shipyard of Rio de Janeiro to which she was then launched on November 4th, 1865. She was finally completed on January 11th, 1866 and entered service to the Brazilian Navy that same year - immediately placed into action.
The Barroso featured a wooden hull with an armored central battery - the superstructure fitted amidships just abaft of a smoke funnel. There were two sail masts (Schooner-rigged sail plan), one on the forecastle and the other towards the stern to which sails could be used for extended, open-seas traveling. Primary propulsion, however, was via 2 x boilers feeding 1 x John Penn & Sons 2-cylinder steam engine to 1 x shaft (total output of 420 horsepower). She measured a hull length of 201 feet, 7 inches, a beam of 36 feet and a draught of 9 feet. Normal displacement was 1,300 tons and the vessel could reach speeds of 9 knots. She was crewed by 149 personnel and armed through 1 x 120-pdr Whitworth rifled gun, 2 x 70-pdr Whitworth rifled guns, 2 x 68-pdr smoothbore guns and2 x 12-pdr smoothbore guns. Armor protection included a belt of 4 inches thickness, a casemate of 4 inches thickness and a deck covering of 0.5 inch thickness.
From 1866 to 1867, the Barroso was utilized against Paraguayan river fortifications, putting her powerful guns to work. She certainly took a battering from Paraguayan guns but suffered no serious damage to her frame - a testament to sound design. The Barroso was eventually used with other allied vessels to bombard the Paraguayan capital of Asuncion. In an attempt to take the Barroso and the ironclad Rio de Janeiro, Paraguayan soldiers canoed their way to the two vessels on July 9th. The vessels were boarded and many of the Rio de Janeiro crew were killed in the fighting. Barroso managed to repulse her boarders and came to the aid of the Rio de Janeiro, tearing through the Paraguayans with salvos of lethal grape shot. The war with Paraguay ended in 1870 with an allied victory and utter destruction for Paraguay in which a large portion of its male population were killed.
Following the war, the Barroso was assigned to the Mato Grosso Flotilla and served in this fashion until 1882 to which she was decommissioned. Amazingly, despite her retired status, the vessel was not broken up and scrapped until 1937 - just prior to World War 2.