Commanded by Captain Phipps Hornby for almost her entire career, Stag began her service in the English Channel, capturing two ships in 1813.

[2] Designed by Surveyor of the Navy Sir William Rule, the Apollo class originally consisted of three ships constructed between 1798 and 1803.

The Royal Navy stopped ordering specifically large and offensively capable warships, and instead focused on standardised classes of ships that were usually more moderate in size, but through larger numbers would be able to effectively combat the expected increase in global economic warfare.

[6] The Apollo class was chosen to fulfil the role of standardised frigate because of how well the lone surviving ship of the first batch, HMS Euryalus, had performed, providing "all-round excellence" according to naval historian Robert Gardiner.

[7] Trials of ships of the class showed that they were all capable of reaching around 12 knots (22 km/h) and were very well balanced, although prone to pitching deeply in heavy seas.

[17][13] Then on 18 April Stag and Unicorn captured the American 2-gun letter of marque schooner Hebe, previously the British HMS Laura, at 47°N 7°W / 47°N 7°W / 47; -7.

[21][22][23] The ships reached Madeira on 21 June, from where Stag parted with the other convoys and sailed with her vessels to the Cape of Good Hope Station.

[26] Still serving at the Cape, in January 1814 Stag was sent to Algoa Bay to search for the merchant ship William Pitt, which was thought to have been wrecked near there in December the previous year.

[27][28] To assist in this Stag took on board a local merchant captain who knew the area, and then sailed from Cape Town, spending three weeks patrolling as far east as the Great Fish River.

Stag and the merchant ship Lord Eldon found wreckage that had drifted ashore in the bay that could be connected to William Pitt.

No structural wreckage from William Pitt was located, but reports of a large ship having passed Algoa Bay on 17 December combined with a strong gale striking St Francis Bay that day, led officials to judge that William Pitt had foundered while attempting to get back out to sea in the night of 17 December.

[34][35][36] On the following morning, the leaking Semiramis was towed into St Helena where the damage was patched, and then sent on with the convoy to England on 24 June in the place of Stag, which returned to the Cape.