She had been designed and laid down for the East India Company, but the Navy purchased her after the start of the French Revolutionary War.

[4] Belmont was registered and named Monmouth on 14 July 1795 and was launched on 23 April 1796, being completed by 31 October 1796 at Deptford Dockyard.

Monmouth was among the seven vessels of Lord Duncan's fleet that shared in the prize money for the privateer Jupiter, captured on 27 April.

[12] Monarch was also part of a squadron that in May captured Roose (12 May), Genet, Polly, American, Forsigtigheid, and Bergen (all 14 May), Des Finch (21 May), and Vrow Dorothea (30 May).

[13] That summer, Monmouth took part in the Helder expedition, a joint Anglo-Russian invasion of Holland under the command of Vice-Admiral Andrew Mitchell.

[18] On 15 September Monmouth, several other British vessels and two Russian, arrived at Sheerness as escort to five Dutch ships of the line, three frigates and one sloop.

[20] Because Monmouth served in the navy's Egyptian campaign (8 March to 8 September 1801), her officers and crew qualified for the clasp "Egypt" to the Naval General Service Medal that the Admiralty authorised in 1850 for all surviving claimants.

There Hart received the report of Captain John Gore of Medusa of his capture of one French felucca-rigged privateer in the Strait, Esperance, and destruction of another, the Sorcier.

After his promotion to rear admiral in April 1804 Thomas McNamara Russell raised his flag in Monmouth for the North Sea.

[4] Rear-Admiral William O'Bryen Drury raised his flag in her on 7 September and then eight days later sailed her with a convoy of nine Indiamen to the East Indies, seven for the coast and two for Bombay.

The vessels she was convoying included Northampton, Sarah Christiana, Ann, Union, Diana, Sir William Pulteney, and Glory.

[25] Then on 12 February she arrived off the Danish possession of Tranquebar just in time to observe the landing of troops of the 14th Regiment of Foot and the Honourable East India Company's artillery by Russell.

In August 1809 Monmouth was at the Walcheren Expedition, the aim of which was to demolish the dockyards and arsenals at Antwerp, Terneuzen, and Flushing.