[4] As the force manoeuvered to clear the minefield, the destroyer Ariel also struck a mine at 00:10 hours on 2 August and, in a repeat of what had happened to Vehement, suffered a magazine detonation that blew off the entire section of the ship forward of the whaleboat's davit.

[4] Vanquisher took part in history's first deployment of operational magnetic bottom mines when she joined Abdiel, Telemachus, and the destroyers Tarpon, Vanoc, and Venturous, escorted by eight other destroyers, in laying 234 Sinker Mk1(M) mines in the North Sea off the coast of Flanders, Belgium, about eight nautical miles (15 km) north of Dunkirk, France, on 8 August 1918.

She also participated with Abdiel, Tarpon, Telemachus, and Venturous in the second operation to lay Sinker mines on 22 August 1918, in the North Sea off Flanders about 17 nautical miles (31 km; 20 mi) north of Zeebrugge, Belgium, supported by Royal Air Force aircraft which patrolled to prevent German aerial observation of the operation.

[6] In 1921, Vanquisher joined the light cruisers Caledon, Castor, Cordelia, and Curacoa and the destroyers Vectis, Venetia, Viceroy, Violent, Viscount, Winchelsea, and Wolfhound in a Baltic cruise, departing the United Kingdom on 31 August 1921.

The ships crossed the North Sea, transited the Kaiser Wilhelm Canal to enter the Baltic, and called at Danzig in the Free City of Danzig; Memel in the Klaipėda Region; Liepāja, Latvia; Riga, Latvia; Tallinn, Estonia; Helsinki, Finland; Stockholm, Sweden; Copenhagen, Denmark; Gothenburg, Sweden; and Kristiania, Norway, before crossing the North Sea and ending the voyage at Port Edgar, Scotland, on 15 October 1921.

[2] Vanquisher, Walker, and Winchelsea escorted Convoy OB 2 on 9 September 1939, and were returning to Plymouth from this duty when Vanquisher and Walker collided in the North Atlantic Ocean about 200 nautical miles (370 km) southwest of Cape Clear Island, Ireland, on 10[8] or 11[2] September 1939 (sources differ).

In May 1940 she was again reassigned, this time under the Commander-in-Chief, Dover to take part in Operation Dynamo, the evacuation of Allied troops from Dunkirk, France, which she joined on 28 May 1940.

On 20 June 1940, she embarked a demolition party and steamed to La Pallice to destroy port facilities there, but did not land the team.

[2] In July 1940, Vanquisher returned to convoy defence duties with the 11th Destroyer Flotilla,[2] and on 8 July 1940 she and the destroyer Scimitar rescued 43 survivors of the British merchant ship Humber Arm, which the German submarine U-99 had torpedoed and sunk in the North Atlantic 60 nautical miles (110 km; 69 mi) south of Fastnet Rock, Ireland, at 50°36′00″N 009°24′00″W / 50.60000°N 9.40000°W / 50.60000; -9.40000 (Humber Arm sunk).

[2] In April 1943, Vanquisher underwent post-conversion acceptance trials, then conducted workups to prepare for operations in the North Atlantic.

In early June, she joined Escort Group 106 at Milford Haven, Wales, and on 4 June the group, supplemented by two more corvettes and the naval trawlers Caldy and Gweal, rendezvoused with an assault convoy, Convoy EMB 3 – consisting of 11 empty motor transport ships – in the Irish Sea.

On 10 April, she and the corvette Tintagel Castle cooperated in a depth-charge attack that sank the German submarine U-878 with all hands in the Bay of Biscay west of Saint-Nazaire, France, at 47°35′00″N 010°33′00″W / 47.58333°N 10.55000°W / 47.58333; -10.55000 (U-878 sunk).