Action of 9 August 1780 The Action of 9 August 1780 was a naval engagement of the American Revolutionary War in which the main Spanish fleet led by Admiral Luis de Córdova y Córdova , together with a squadron of French ships , captured a heavy British convoy of sixty - three vessels causing a severe blow to the commerce of Great Britain . The British convoy led by Sir John Moutray , captain of and three frigate s sailed from Portsmouth in late July , and were intercepted on 9 August by the Spanish fleet . During the action the Spaniards managed to capture 55 of 63 vessels , making it one of the most complete naval captures ever made . This loss was still bitterly remembered in Great Britain thirty years later at the height of the Napoleonic Wars . The British financial losses were estimated at £1 , 500 , 000 . Besides the loss of the merchantships , 3144 men , and goods worth £1 , 5 million , the convoy ' s capture offset Admiral Rodney ' s victory in the Moonlight battle and helped derail a secret British diplomatic effort to make a separate peace with Spain . Engagement . On the morning of 2 August , the Channel Fleet fell in with a large outward - bound British convoy under the escort of HMS " Ramillies " and four frigates . This convoy sailed from Portsmouth and consisted of sixty three sail , including not only East and West India ships but also victuallers , military storeships , and transports carrying the 90th Regiment of Foot . The Channel Fleet accompanied the convoy for several hours to a point 112 leagues off the Isles of Scilly , where the two groups of ships parted company . Following the instructions given by Don Jose Moñino , count of Floridablanca to Luis de Córdova , the Spanish fleet put sail from Cádiz and sailed as far as Madeira and the Canary Islands , where Don Luís deployed several frigates to spot the convoy , being finally intercepted in the night of the 9th August by one of the Frigates . The news were greeted with caution because there was doubt whether the sails detected corresponded to the Channel Fleet or whether it was the convoy heavily escorted . The second Spanish command , José de Mazarredo called immediately for an attack , which meant that there was no reason for the British fleet to risk themselves sailing so far from their coast . Proposing that all the suspected sails had to be escorted . The British mistook the lanterns at mast head of the " Santísima Trinidad " for those of their own commander , and fooled by a " ruse of war " steered accordingly . At break of day , they found themselves intermingled with the Spanish fleet . Admiral de Cordova enveloped them , and hoisted signals of " general chase " . The convoy included , besides the merchantmen , eighteen victuallers , storeships , and transports , destined for the service in the West Indies ; one of these was of particular importance , being laden with tents and camp equipage , for the troops designed for active service in the Leeward Islands . The five East India vessels , besides arms , ammunition , and a train of artillery , conveyed a large quantity of naval - stores , for the supply of the British squadron in that quarter . These ships , and above fifty West Indiamen , including those chartered by the crown , were seized by de Córdova ' s fleet . The five East Indiamen were the " Gatton " , " Godfrey " , " Hillsborough " , " Mountstuart " and " Royal George " , and their loss represented the worst disaster in history for the East India Company . The " Mountstuart " and " Godfrey " were shelled by the 120 - gun ship of the line " Santísima Trinidad " , flagship of Admiral de Córdova , before surrendering to the Spanish . " Gatton " was also hit by the " Purísima Concepción " and set alight , but the fire was later put under control and the ship seized . A frigate flotilla , commanded by Santiago de Liniers and part of the " Concepción " squadron , captured the 30 - gun " Hillsborough " . HMS " Ramillies " , two frigates and few West - India ships broke contact and sailed away . The official Spanish report identifies the frigates as the 36 - gun HMS " Thetis " and HMS " Southampton " . The captured British ships , numbering nearly 60 , were brought into Cádiz , an unusual spectacle since the capture of such a great enemy convoy by any navy was an uncommon event ; de Córdova ' s fleet produced this feat upon two occasions . All the ships including the five East Indiaman were brought into the Spanish navy . This was a major intelligence failure , for the British Admiralty did not learn of the sailing of this enemy fleet until 4 August and neither Geary nor Captain John Moutray . Aftermath . This Spanish victory , compounded by the serious storm losses in the Caribbean , produced a financial crisis among the marine insurance underwriters throughout Europe . Many went bankrupt , and war insurance rates , already remarkably high due to the menacing presence of privateers , were driven to intolerable levels . It also increased and made increasingly public the dissatisfaction which had before prevailed against the ministry , and against the conduct and government of the Royal Navy . The five British East Indiaman were brought into Spanish service , giving them an entire squadron of frigates . Thus , the 30 - gun " Hillsborough " was commissioned in the Spanish navy as 34 - gun " Santa Balbina " , the 28 - gun " Mountstuart " as 34 - gun " Santa Bibiana " , the 28 - gun " Royal George " was brought into Spanish service as 40 - gun " Real Jorge " , the 28 - gun " Godfrey " commissioned as 34 - gun " Santa Paula " and the 28 - gun " Gatton " was brought into Spanish service as 30 - gun " Colón " . The Spaniards behaved with great humanity to their prisoners , repaying the generous treatment which their countrymen had experienced from Admiral Rodney .