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 Beresford.

The frigate was under the command of Captain Chaloner Ogle as one of Nelson's scouts, but not present at Trafalgar; instead, she lay dismasted in Lisbon harbour.

[Note 1] 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.

[9] Admiral Sir Charles Cotton, commander in chief of the British Mediterranean Fleet, decided to buy her and her stores for the Royal Navy.

[10] 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.