HMS Thunder was an 8-gun bomb vessel of the Royal Navy, previously the mercantile Dasher.

Dasher, launched at Bideford in 1800, had made two voyages as a slave ship in the triangular trade in enslaved people before the Royal Navy purchased her in 1803 and renamed her HMS Thunder.

[2][a] In April 1803, War with France had just resumed and the Royal Navy needed small warships to escort convoys and combat privateers.

[10] On 17 November, Thunder detained the Prussian ship Minerva, of one gun, six men and 200 tons (bm).

Ten days later, Thunder detained the Swedish ship St. Jean, of two guns, eight men, and 150 tons (bm).

St Jean had been sailing from Vigo to Stralsund with cocoa and fish when Thunder captured her off Malaga.

Next, Thunder detained Fremde Soshende, Thompson, master, which had been sailing from Malaga to Embden, and sent her into Gibraltar.

[21] HMS Dexterous and Niger were in company with Thunder at the capture of Trende Damen (Three Ladies).

[25] Later in the year Thunder detained and sent into Gibraltar the Danish vessel Louisa, Martins, master.

She was part of the advanced squadron which on 11 September engaged some Danish vessels that came out of the harbour at Copenhagen to attack the batteries the British army was establishing on shore.

The merchants at Lloyd's involved in the Baltic trade, as a token of appreciation for his efforts to save the convoy, gave Commander Caulfield £100 with which to purchase a piece of silver plate.

When Admiral Saumerez instructed Caulfield to withdraw he requested permission to remain a little longer.

[30] After the British and the Swedes abandoned the blockade in the face of the approaching winter, the Russian fleet was able to return to Kronstadt.

She did not participate in the original attack on 11 April, but after the French 74-gun Régulus stranded on a shoal at the entrance to the Charente, Thunder shelled her, but without success.

[31] On 22 August, HMS Hound, Aetna, and Thunder were by the town of Doel and fired mortar shells to deter the French from throwing up a battery.

Through the 30th the bomb vessels continued to shell the battery, and also enemy troops on the other side of the Scheldt.

During the first week in September the British started to withdraw, ending their Walcheren campaign, having sustained heavy losses to disease and having nothing to show for their efforts.

The French had assembled a flotilla of gun-boats to attack the town so on 23 November Thunder, Devastation, and Aetna, with a number of English and Spanish mortar and gun-boats, attacked the French flotilla at El Puerto de Santa María, between them firing some hundred shells with considerable effect.

[32] In early 1812, HMS Stately, Druid and Thunder supported the British capture of Tarifa, near Cadiz.

[33] Thunder then returned to her station at Cadiz by Fort Catalina at the southern end of the Bay of Bulls, and protected Isla de León.