He entered the Navy on 6 September 1799 as a first-class volunteer aboard the sloop , employed in home waters under Commander John Watts. From December 1800 he served in the Mediterranean, as midshipman, master's mate, and for a short time as acting-lieutenant; firstly aboard the frigate , under Captains
George Johnstone Hope and
Robert Honyman, seeing action in the Egyptian campaign under the former. He then followed Captain Hope into the
74s , taking part in the battle of Trafalgar on 21 October 1805, and . Finally, he served aboard , under Captain
Peter Parker, from where he was promoted to lieutenant on 20 August 1806. For the next seven years Plumridge served as a lieutenant; aboard the under Captain the Honourable
Arthur Kaye Legge, in under Captains
John Giffard and
William Pierrepont, and then
Melpomene again, under Captain Peter Parker. There, on 1 May 1809, during the
Gunboat War, he commanded the boats of
Melpomene in an attack on a Danish cutter of 6 guns and several merchantmen, which were lying under the protection of gun batteries in the harbour of Huilbo,
Jutland. The cutter was destroyed, but with the loss of Lieutenant George Rennie, and five men severely wounded. Soon after
Melpomene fought off an attack by a flotilla of 20 gun-boats, suffering considerable damage, and losing 34 men killed and wounded. He then served aboard the frigate , Captain
Joseph Baker, in the Baltic. By December 1810 Plumridge was serving aboard the frigate under Captain Peter Parker again, and taking part in the capture of
Isle de France. He then served aboard the 80-gun ship , Captain
Sir John Gore; in and , the flag-ships of Sir
William Sidney Smith in 1812; and the frigate , Captain
Fleetwood Pellew. On 5 October 1813 he commanded the boats of
Resistance at the destruction of batteries and the capture of a convoy in
Porto d'Anzo. He then served aboard , Captain Thomas Gordon Caulfeild, and , the flagship of Sir
Edward Pellew. In April 1814 he served as Pellew's
aide-de-camp during the capture of
Genoa. ==Peacetime service==