'DX' was a British carrierborne air undertaking by Admiral Sir Charles Forbes’s Home Fleet to provide air cover for the Allied forces in northern Norway after the 'Weserübung' invasion and following German land operations (23/27 April 1940).

The force which left Scapa Flow on 23 April to replace that centred on the fleet carrier Furious off Narvik on the coast of northern Norway comprised the fleet carriers Ark Royal and Glorious, the heavy cruiser Berwick, the light anti-aircraft cruiser Curlew, and the destroyers Fearless, Fury, Hasty, Hyperion and Juno. On the following day the force began operations off Norway in support of the Allied forces ashore, and Gloster Gladiator single-engined biplane fighters were flown off to establish a base on a frozen lake in the Romsdal.

The force continued operations on 25 and 26 April, latterly with the screen provided by the destroyers Beagle, Encounter, Escort, Fury, Grenade and Volunteer.

Having lost four Blackburn Skua single-engined attack aircraft, Glorious then had to break off to return to Scapa Flow to refuel and rearm. Even though not all the expected aircraft replacements had been delivered, the carrier departed for Narvik once again on 30 April after a delay imposed by the weather. On this occasion the destroyer escort included Acheron, Antelope and Beagle.

On 1 May Glorious rejoined Ark Royal, and the two carriers then provided cover for the 'Brick' and 'Tunnel' (i) evacuations from Åndalsnes and Molde, as well as undertaking anti-submarine patrols and air cover for the protection of the fleet and shipping.

On the same day Glorious and Berwick escorted the battleship Valiant, and came under heavy German air attack. On the followed day Ark Royal and Glorious returned to Scapa Flow.