HMS Encounter was ordered as a First-Class Sloop with screw propulsion on 5 February 1845 to be built at Pembroke, in accordance with the design developed by John Fincham, Master Shipwright at Portsmouth.

A second vessel (Harrier) was ordered on 26 March 1846 but after her keel was laid at Pembroke Dockyard, her construction was suspended on 9 September 1846 then cancelled five years later, on 4 April 1851.

The intention was to trial different types of vessels in a variety of sea and wind conditions, with the aim of building experience of the comparative characteristics of new ships.

For the Naval Review on the 10th of August 1853, she was in the port column, led by the new 91-gun, second rate, HMS Agamemnon (flying the flag of Rear Admiral Armar Lowry-Corry).

Encounter took part in April 1854 in joint British-American operations against Chinese imperial troops in Shanghai with HMS Grecian and USS Plymouth.

Imperial Chinese troops had begun assaulting foreigners, sacking warehouses, and exacting tolls on boats sailing up and down the Huangpu River.

Supported by gunfire from two privately owned field pieces and a howitzer, the Allied force routed the Chinese defenders, who "fled in great disorder, leaving behind them a number of wounded and dead."

Admiral Stirling, wishing to prevent Russian ships from sheltering in Japanese ports to interdict British merchant vessels, concluded the Anglo-Japanese Friendship Treaty with representatives of the Tokugawa Shoganate at Nagasaki in October 1854.

On 1 June 1855 a squadron consisting of Encounter, Pique, Dido, Brisk, Barracouta and the French frigate Alceste entered the harbour of Petropavlovsk.

On 3 June, Encounter, Barracouta and Pique sent armed boats to Rakouina Harbour to capture the Russian whaler Aian.

On 7 October 1856, Encounter assisted in the refloating of the British merchant ship Inchinnan,[5] which had been driven ashore at Shanghai on 4 September.

[3] Between 11 May and 15 December 1862 Encounter's commanding officer, Captain Roderick Dew, in charge of a squadron of French and English gunboats supported Chinese troops in action against rebel and pirate forces attacking the treaty ports.