Battle of Cape St . Vincent ( 1833 ) The fourth Battle of Cape St Vincent was fought on 5 July 1833 and was a decisive encounter in Portugal ' s Liberal Wars . A naval squadron commanded by the British officer Charles Napier , on behalf of Dom Pedro IV , regent for the rightful Queen Maria II , defeated the navy of the usurper Dom Miguel . Background . While serving in the Azores , Napier had come to know members of the exiled Portuguese liberals , who had offered him command of the small fleet serving Dom Pedro , which largely consisted of a few old men - o ' - war and some East Indiamen purchased from the British . In February 1833 Napier accepted their proposals , in succession to another British officer , Captain George Rose Sartorius , who was already serving as Admiral of Pedro ' s navy . Using the name ' Carlos de Ponza ' in a transparent attempt to disguise his identity as a British officer to escape penalties under the Foreign Enlistment Act , in June 1833 Napier joined his new command in the Douro River off Oporto . ( ' Carlos de Ponza ' = Charles of Ponza ; one of Napier ' s most daring feats in the Napoleonic War had been the capture of the island of Ponza in the Mediterranean in 1813 ) . Dom Pedro , currently being besieged in Oporto by the forces of Dom Miguel , bestowed on Napier his commission as Vice Admiral , Major General of the Portuguese Navy and Commander in Chief of the fleet . An eccentric but indomitable character , Napier restored the situation in the fleet , which had been close to mutiny because of lack of pay , and proposed a new strategy to break the siege . Flying his flag in the frigate " Rainha de Portugal " 46 , commanded by Captain F . G . MacDonough and with his stepson Charles Elers Napier as Chief of Staff , on 20 June he sailed from Oporto with his small fleet , transporting the Duke of Terceira and half the constitutional army to the Algarve so that they could open a second front in the south of the country and march on Lisbon . After successfully disembarking this force , on the return voyage he encountered the considerably superior fleet of Dom Miguel off Cape St Vincent on 3 July 1833 , and after two days of maneuvering in calm and very light winds he brought them to action . The battle . Napier ’ s command was essentially a mere squadron of six ships : three frigates , a corvette , a brig and a schooner , mounting a total of 176 guns . ( He had some small steamers under his command which he hoped to use as tugs , but they abandoned him while the two forces were becalmed on the 4th of July : thus the subsequent battle was perhaps the last engagement of consequence between two fleets of sailing warships . ) On 5 July the wind eventually got up and at 4 . 00 p . m . he attacked the Miguelite force of 3 ships of the line , a frigate , a xebec , 3 corvettes and 2 brigs , mounting altogether 372 guns . Knowing he could not long sustain a cannonade from such a superior opponent , Napier closed against enemy fire and boarded , so that the battle was decided in hand - to - hand fighting . In the event the Liberal forces captured all three ships of the line , a frigate and a corvette , whose crews agreed to fight from now on for Maria II ; another ship came over the next day ; the remnant of the Miguelite force fled to Lisbon or Madeira . Napier ’ s losses were about 30 killed ( including the captain of " Rainha de Portugal " and two other captains ) and about 60 wounded ( including Charles Elers Napier ) , as against somewhere between 200 and 300 of the enemy , including the Miguelite commander , Admiral Manuel António Marreiros . On 6 July , receiving news of the victory , Dom Pedro named Napier as Viscount Cape St Vincent in the peerage of Portugal . Immediately afterwards his fleet was ravaged by cholera ( which was raging on mainland Portugal ) , with appalling loss of life , but he was able to bring it safe into Lisbon , which the Miguelistas had precipitately abandoned after being defeated by Terceira ’ s army advancing from the south at the Battle of Almada . Napier visited Rear - Admiral Sir William Parker of the British navy who was in the vicinity of the Tagus , and was received according to his Portuguese rank as an Admiral . Though he was subsequently struck off the Navy List at the insistence of the French , he was restored to his rank in the Royal Navy within two years and the Battle , largely won by British officers and crews fighting for Maria II , was viewed in England as bringing honour to the British navy . The sea victory , making possible the capture of Lisbon from the Miguelites , was the single most important event contributing to Miguel ' s eventual defeat and overthrow in 1834 . Ships involved . Loyalist fleet ( Charles Napier ) . " Rainha de Portugal " 46 ( flag , commodore Wilkinson , captain MacDonough ) < br > " Dona Maria " 42 ( Peake ) < br > " Dom Pedro " 50 ( Thomas Goble ) < br > " Vila Flor " 18 ( Ruxton ) < br > " Portuense " 20 ( Blackstone ) < br > " Faro " 6 < br > a few steam tugs and transports Miguelite fleet ( Manuel António Marreiros ) . " Nau Rainha " 74 ( Barradas ) - Captured by " Rainha de Portugal " < br > " Dom João " 74 - Captured < br > " Martinho de Freitas " 50 - Captured < br > " Duquesa da Bragança " 56 - Captured by " Donna Maria " < br > " Isabel Maria " 22 ( corvette ) - Captured < br > " Princesa Real " 24 ( corvette ) < br > " Tejo " 20 ( corvette ) < br > " Sybille " 20 ( corvette ) < br > " Audaz " 18 ( brig ) < br > " Activa " ( xebec ) < br > several other brigs Sources . Main source for this entry is Napier ' s own narrative of the battle in his " An Account of the War in Portugal between Dom Pedro and Dom Miguel " ( London , 1836 )