Brazilian ironclad Barroso The Brazilian ironclad " Barroso " was an armoured gunboat built for the Brazilian Navy during the Paraguayan War in the mid - 1860s . " Barroso " bombarded Paraguayan fortifications in 1866 and 1867 a number of times before she participated in the Passagem de Humaitá in February 1868 . Afterwards the ship provided fire support for the army for the rest of the war . She was assigned to the Mato Grosso Flotilla after the war . " Barroso " was decommissioned in 1882 , but was not scrapped until 1937 . Design and description . " 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 ship is best characterized as a central battery design because the casemate did not extend the length of the ship . A bronze ram , long , was fitted . The hull was sheathed with Muntz metal to reduce biofouling . For sea passages the ship ' s free board could be increased to by use of removable bulwarks high . On riverine operations , the bulkwarks and the ship ' s masts were usually removed . The ship measured long overall , with a beam of and had a mean draft of . " Barosso " normally displaced and at deep load . Her crew numbered 149 officers and men . Propulsion . " Barroso " had a single John Penn & Sons 2 - cylinder steam engine driving a single 2 - bladed propeller . Her engine was powered by two tubular boilers . The engine produced a total of which gave the ship a maximum speed of . The ship ' s funnel was mounted directly in front of her casemate . " Barroso " carried enough coal for six days ' steaming . Armament . " Barroso " mounted one 120 - pdr Whitworth and two 70 - pounder Whitworth rifled muzzle loader s , two 68 - pounder and two 12 - pounder smoothbore guns in her casemate . To minimize the possibility of shells or splinters entering the casemate through the gun ports they were as small as possible , allowing only a 24° - arc of fire for each gun . The rectangular , casemate had two gun ports on each side as well as the front and rear . The shell of the 120 - pounder gun weighed while the gun itself weighed . The 70 - pdr gun weighed and fired a shell that weighed . The solid shot of the 68 - pounder gun weighed approximately while the gun itself weighed . The gun had a range of at an elevation of 12° . The exact type of 12 - pounder gun is not known . All of the guns could fire both solid shot and explosive shells . Armor . The hull of " Barroso " was made from three layers of wood , each thick . The ship had a complete wrought iron waterline belt , high . It had a maximum thickness of covering the machinery and magazine s , elsewhere . The curved deck , as well as the roof of the casemate , was armoured with of wrought iron . The casemate was protected by 102 millimetres of armour on all four sides , backed by of wood capped with a 102 mm layer of peroba hardwood . Service . " Barroso " was laid down at the Arsenal de Marinha da Côrte in Rio de Janeiro on 21 February 1865 . She was launched on 4 November 1865 and completed on 11 January 1866 . On 26 – 28 March 1866 she bombarded the Paraguayan fortifications at Curupaity where she was hit 20 times , but not significantly damaged . The ship bombarded Curuzu Fort , downstream of Curupaity , on 1 September in company with the ironclads , , , , and the monitor . The ships bombarded Curupaity again on 4 September and " Barroso " was hit four more times . 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 . Between 24 and 29 December " Barroso " , " Tamandaré " , " Brasil " , and 11 gunboats bombarded Curuzu Fort again . The Brazilians broke through the river defences at Curupaity during daylight on 15 August 1867 with " Barroso " , " Tamanadaré " , and eight other ironclads . The ships were hit 256 times , but not seriously damaged , and only suffered 10 killed and 22 wounded . They repeated the operation again on 9 September . On 19 February 1868 six Brazilian ironclads , including " Barroso " , sailed past Humaitá at night . Three river monitor s , , and were lashed to the larger ironclads in case any engines were disabled by the Paraguayan guns . " Barroso " led with " Rio Grande " , followed by " Bahia " with " Alagoas " and " Tamandaré " with " Pará " . " Barroso " continued upstream with the other undamaged ships and they bombarded Asunción on 24 February . 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 . After the war the ship served with the Mato Grosso Flotilla and was decommissioned in 1882 . However , " Barroso " was not scrapped until 1937 .