South America in support of a second failed attempt to wrest the River Plate area from the Spanish. A detachment of sailors and marines from Polyphemus served on shore in the Advance Brigade during the disastrous (for the British) attack on Buenos Aires. Admiral Murray evacuated Lieutenant Crowley of Polyphemus, who had been wounded, and his men, aboard the frigate . Polyphemus remained in the River Plate area, carrying out surveying and merchant vessel protection duties. Between January and February 1808 Polyphemus underwent a refit at Portsmouth. Heywood remained in command until May 1808, when Captain William Pryce Cumby replaced him. Cumby had been lieutenant and then acting commander of at Trafalgar. Polyphemus became the flagship of Vice-Admiral Bartholomew Samuel Rowley. In July she sailed for Jamaica, convoying a large fleet of merchantmen, and taking the Vice-Admiral to take up his appointment as chief of the station. Since he resided on shore with his flag in , Polyphemus was able to undertake cruises against the enemy. On the morning of 14 November Cumby sent his boats, under Lieutenant Joseph Daly in the barge, to chase a schooner attempting to enter the harbour at San Domingo. An hour later the British succeed in boarding the schooner despite facing a hail of grape and musketry. Their quarry proved to be the French navy schooner Colibry, of three carriage guns and a crew of 63 men under the command of lieutenant de vaisseau Deyrisse. The French lost one man killed and five wounded; Polyphemus had one man killed. On 17 April 1809, a British squadron captured the French 74-gun during Troude's expedition to the Caribbean. The initial distribution of prize money excluded Polyphemus and Tweed, who appealed. Polyphemuss appeal succeeded. On 28 April Polyphemus recaptured Carlotta, Duncan, master, and sent her into Jamaica. Carlotta had been sailing from St Batholomew's to Jacmel when a French privateer captured her. In June 1809 Cumby received command of a squadron consisting of Polyphemus, , , , , , , , , and . They sailed from Port Royal on 7 June with troops under Major-General Hugh Lyle Carmichael to assist the Spanish forces besieging the French in the city of San Domingo. On 1 July Polyphemus anchored at Caleta and loaded eight of her 24-pounder guns into Sparrow for landing at Palenqui for the use of the batteries west of the city. Captain Burt of Sparrow