The Impérieuse was a 40-gun Minerve-class frigate of the French Navy. The Royal Navy captured her in 1793 and she served first as HMS Imperieuse and then from 1803 as HMS Unite. She became a hospital hulk in 1836 and was broken up in 1858.
In 1788, Imperieuse cruised in the Middle East, and the Aegean Sea the two following years. She performed another cruise off the Middle East before returning to Toulon. On 11 October 1793, Impérieuse was captured off La Spezia by HMS Captain and the Spanish ship of the line Bahama following the Raid on Genoa.
The Royal Navy commissioned Imperieuse as the fifth rate frigate HMS Imperieuse.
Imperieuse entered service in 1795, and operated in the West Indies off Martinique and Surinam for most of the French Revolutionary Wars, under the command of Captain John Poo Beresford. Imperieuse returned to Britain at the Peace of Amiens.
When the Napoleonic Wars Imperieuse was renamed Unite and eturned to service in the Mediterranean. The frigate was under the command of Captain Chaloner Ogle as one of Nelson scouts, but not present at Trafalgar; instead, she lay dismasted in Lisbon harbour.
Unité, Melpomene and Weazel shared in the capture of the Buona Esperanza on 19 July 1807 and the Bizzaro, on 21 August. The bankruptcy of the prize agents meant that some prize money was not distributed until 21 years later, in 1828. The fourth and final payment for Bizzarro did not occur until July 1850.
Under Captain Patrick Campbell Unite was the first frigate to enter the Adriatic Sea and during the spring of 1808 captured a string of French and Italian gunboats and coastal merchant vessels, notably the 16-gun sister-brigs Ronco, Teulié and Nettuno, the first on 2 May 1808 off Cape Promontore, Istria, and then the second two on 1 June 1808 off Zara. Campbell reported no casualties in the capture of Ronco. Teulié lost five men killed and 16 wounded before she struck; Nettuno lost seven killed, two drowned, and 13 wounded. The Royal Navy took all three into service, Ronco under the name HMS Tuscan, Teulié under the name HMS Roman, and Nettuno under the name HMS Cretan.
On 19 May 1810 Unite captured the French privateer Du Guay Trouin of 10 guns and 116 men.
By 1811 Unite was still operating in the Mediterranean, under Captain Chamberlayne.
On 31 March 1811, Unite and Ajax encountered a French squadron comprising the frigates Adrienne and Amélie, and the armed transport French corvette Dromadaire. Ajax captured Dromadaire, while the frigates managed to escape to Portoferraio. Captain Otway of Ajax reported that Dromadaire was frigate-built and sailed remarkably well. Her cargo consisted of 15,000 shot and shells of various sizes and 90 tons of gunpowder. Apparently Napoleon Bonaparte intended them as a present for Hammuda ibn Ali, the Bey of Tunis. Admiral Sir Charles Cotton, commander in chief of the British Mediterranean Fleet, decided to buy her and her stores for the Royal Navy.
On 1 May, Unite participated in the destruction of the French vessels Giraffe, Nourrice, and an armed merchant man sheltering near the island at Sagone, with the help of HMS Pomone and HMS Scout.
Through the summer Unite operated off the mouth of the Tiber and in the autumn she was once again sent to the Adriatic, participating in the Action of 29 November 1811 at which she captured the armed storeship Persanne.
On 16 June 1812 boats from Unite, Orlando and Cerberus captured three vessels of from eighty to one hundred tons in the small port of Badisea, near Otranto.
On 9 November 1812 Unite was in sight when Furieuse captured Nebrophonus.
By 1815, Unite was back in Britain in reserve at Deptford and she remained there until converted for harbour service in 1832. Between 1841 and 1858, she was used as a prison hulk. The ship was eventually broken up in January 1858 at Chatham Dockyard.