During World War II, she served as a convoy escort in the battle of the Atlantic, on anti-submarine patrols during the invasion of Normandy, and was employed as a troop transport after VE Day for returning Canadian servicemen, before being decommissioned in late 1945.

Comet carried a maximum of 473 long tons (481 t) of fuel oil that gave her a range of 5,500 nautical miles (10,200 km; 6,300 mi) at 15 knots (28 km/h; 17 mph).

[6] On 9 August she assisted the crew of the crippled British yacht Blue Shadow off Gijon, after the small vessel was shelled by mistake by the Nationalist cruiser Almirante Cervera.

Two of her sisters were chosen instead and Comet was recommissioned for service with the Mediterranean Fleet as plane guard for the aircraft carrier Glorious on 29 December.

[6] In April 1937 she returned to Portsmouth with Glorious, and on 20 May the ship participated in the Coronation Review of the fleet at Spithead by King George VI.

After returning to England, Restigouche escorted several troop convoys on the last legs of their journeys from Canada, Australia and New Zealand in mid-June.

On 23 June, the ship escorted the ocean liner SS Arandora Star to St. Jean de Luz to evacuate Polish troops and British refugees trapped by the German Army in south-western France (Operation Aerial).

Struck forward of the bridge by the cruiser's bow, Fraser was cut in half, although the rear part of the ship did not immediately sink.

[13] Upon its completion, Restigouche remained at Halifax for local escort duties until January 1941 when she sailed for the UK where she was reassigned to the Western Approaches Command.

[14] Whilst guarding the battleship Prince of Wales at Placentia Bay on 8 August, Restigouche damaged her propellers when she struck bottom and required repairs that lasted until October.

Repairs at Greenock lasted until 9 March 1942[13] and her director-control tower and rangefinder above the bridge had been removed by this time in exchange for a Type 271 target indication radar.

In June–July 1944, Restigouche patrolled in the English Channel and the Bay of Biscay hunting for German submarines trying to sink Allied shipping.

[13] On the night of 5–6 July, the ship and the rest of the 12th Escort Group sank three small German patrol boats off Brest.

This lasted until the end of the war in May, after which the ship was used to transfer returning troops from Newfoundland to mainland Canada until she was paid off on 5 October.