Argus also evaluated various types of arresting gear, general procedures needed to operate a number of aircraft in concert and fleet tactics.

Argus was recommissioned and partially modernised shortly before the Second World War and served as a training ship for deck-landing practice until June 1940.

In November, the ship provided air cover during Operation Torch, the invasion of French North Africa, and was slightly damaged by a bomb.

In 1912, the ship builder William Beardmore and Company had proposed to the Admiralty an aircraft carrier design with a continuous, full-length flight deck, but it was not accepted.

Construction of the Italian ocean liners Conte Rosso and Giulio Cesare had been suspended by Beardmore at the outbreak of the war, and both met the Admiralty's criteria.

Conte Rosso was purchased on 20 September 1916, possibly because her machinery was more complete than that of Giulio Cesare, and the company began work on converting the ship.

[2] James Graham, 6th Duke of Montrose, a director of the Beardmore company, proposed to the Admiralty a design, "A Parent Ship for Naval Aeroplanes and Torpedo Boat Destroyer" in 1912.

[3] In November 1916, the ship's design was tested in a wind tunnel by the National Physical Laboratory to evaluate the turbulence caused by the twin islands and the bridge over them.

In April 1918, Argus was ordered to be modified to a flush-decked configuration after the sea trials of the carrier Furious had revealed severe turbulence problems caused by her superstructure.

Despite having been originally conceived as a liner with a hull designed to minimise rolling, most of the changes made to the ship during her conversion added topside weight, raising her centre of gravity.

The ship carried 2,500 long tons (2,500 t) of fuel oil, which gave her a range of 3,600 nautical miles (6,700 km; 4,100 mi) at 10 knots (19 km/h; 12 mph).

[8] Argus was the only British carrier serving in the Second World War capable of striking down (stowing away) aircraft with non-folding wings because of her wide lifts and tall hangar ceiling.

[15] After commissioning too late to participate in the First World War, Argus was tasked to conduct deck-landing trials with longitudinal arresting gear transferred from Furious.

Argus joined the Atlantic Fleet in January 1920 for its Spring Cruise carrying a total of sixteen airplanes: eight Ship Strutters, four Sopwith Camel fighters, two Airco DH.9A bombers and two Fairey floatplanes.

Operational experience confirmed that the aircraft should attempt to land directly onto the arresting gear lest they be blown over the side of the carrier, as happened three times during the cruise.

As well as operating her own aircraft, Argus was used to fly off Bristol Fighters that had been ferried to the Dardanelles aboard the seaplane carrier Ark Royal to an airfield at Kilia on the European side of the straits.

[18] In July 1922, Argus was inclined to evaluate her stability in light of the additional weights that had been added since her completion and it was discovered that her metacentric height had been reduced by 0.83 feet (0.3 m).

Since she was completed before 9 December 1921, the Washington Naval Treaty classified her as an experimental aircraft carrier and thus she did not need to be scrapped to release treaty-limited tonnage for new construction.

[25][26] Together with the battlecruiser Hood and six destroyers, Argus escorted Convoy US-3, loaded with Australian and New Zealand troops, to the United Kingdom in mid-June.

Argus loaded a dozen Hawker Hurricane and two Blackburn Skua fighters of 418 Flight RAF in late July for delivery to Malta as part of Operation Hurry.

Escorted by Ark Royal, three battleships, two cruisers and 10 destroyers, the ship flew them off without incident on 2 August 1940 from a point west of Sicily, although two of the Hurricanes crashed on landing.

Eight of the Hurricanes ran out of fuel en route due to headwinds and one Skua was forced to crash land on Sicily after it had been damaged by Italian flak.

No air strike could be flown against the German cruiser because the Swordfish were embarked in Argus with bombs that they could not carry and the torpedoes were aboard Furious.

Two days later, the two carriers, in Operation Perpetual, sailed to the west of Sicily and flew off their 37 Hurricanes; three of the fighters were lost en route.

During Operation Picket I, nine more Spitfires were flown off by Eagle on 21 March whilst a dozen Sea Hurricane IIBs from 804 Squadron provided air cover from Argus.

The two carriers repeated the delivery on 29 March when Eagle flew off seven more Spitfires whilst 807 Squadron provided air cover from Argus.

As usual, Argus provided the air cover with a dozen Fulmars from 807 Squadron and Eagle ferried the Albacores and 17 Spitfires to their take-off point for Malta on 19 May.

The ship rendezvoused with the other carriers on 5 August for a three-day training exercise to work out co-ordination procedures before the operation commenced and 804 Squadron was deemed not ready for combat.

[40][41] In November 1942, Argus was assigned to the Eastern Naval Task Force that invaded Algiers, Algeria, during the Allied landings in French North Africa with 18 Supermarine Seafire IICs of 880 Squadron aboard.

[45] The ship's bell from Argus is preserved in Bristol Cathedral as a memorial to Canon Percival Gay, who was the warship's last chaplain.