Her completion was delayed by labour troubles and the possibility that she might be repurchased by Chile for reconversion into a battleship, as well as the need for comparative trials to determine the optimum layout for aircraft carriers.

The ship was initially assigned to the Mediterranean Fleet and then later to the China Station, spending very little time in home waters other than for periodic refits.

During the early part of the war, the Fleet Air Arm was desperately short of fighters and Eagle was equipped solely with Fairey Swordfish torpedo bombers until late 1940.

After completing an extensive refit in early 1942, the ship made trips delivering fighter aircraft to Malta to boost its air defences in the first half of 1942.

The anti-aircraft armament was reduced to a single 4-inch gun mounted on the island between the funnels as Beatty believed that the ship's own fighters would be her best defence against enemy aircraft.

[5] Construction was slowed by industrial action after the war, and was suspended on 21 October 1919 as Chile wanted to repurchase the ship and have it re-converted to a battleship.

The Royal Navy needed to carry out flying trials with a carrier fitted with an island, and the Admiralty approved the use of Eagle on 11 November.

The shape and size of the island was modified in accordance with the results from wind tunnel testing at the National Physical Laboratory, but the 6-inch guns were retained.

After construction began, anti-torpedo bulges were added, 6 feet (1.8 m) deep, and the petrol tin storage room was replaced by a 8,100-imperial-gallon (37,000 L; 9,700 US gal) tank.

Eagle sailed for Devonport at the end of 1925 for a brief refit where the longitudinal arresting gear was removed as it had been found to be virtually useless in service.

On 29 June 1929, she rescued Spanish Air Force Major Ramón Franco – brother of future Spanish dictator Francisco Franco – and his crew, who had been adrift in the North Atlantic Ocean since 22 June when their flying boat, the Dornier Do J Wal ("Whale") Numancia was forced down due to fuel exhaustion on the first leg of an attempt to fly westward around the world.

Eagle departed Malta on 8 January 1931, en route to Portsmouth to load the latest carrier aircraft for a demonstration at the British Industries Exhibition at Buenos Aires, Argentina.

The tropical heat caused problems in cooling the bomb magazines, and the food storage rooms and the ventilation proved to be barely satisfactory.

She put to sea a few days later and began searching for German merchant ships in company with the light cruiser Birmingham and escorted by the destroyer Daring.

A Swordfish discovered the freighter SS Franken south of the port of Padang on Sumatra and Birmingham was ordered to intercept it while Eagle continued her air patrols.

She arrived in Colombo, Ceylon, on 10 September and until 5 October she searched the Indian Ocean for German ships between the west coast of India and the Maldive Islands with the light cruiser Liverpool.

Eagle was then assigned to Force I together with the heavy cruisers Cornwall and Dorsetshire, to search the Indian Ocean for the pocket battleship Admiral Graf Spee and other German commerce raiders.

[32] Eagle continued to patrol the Indian Ocean in 1940, but escorted a large Australian troop convoy to Suez early in the year.

In June three crated Gloster Sea Gladiators were found in storage at Dekheila and these aircraft became the only fighters available for the entire fleet in the Eastern Mediterranean.

[38] On the night of 20 July, six aircraft from 824 Squadron, flying from Sidi Barrani,[39] sank the destroyers Nembo and Ostro as well as the freighter SS Sereno.

[40] While providing distant cover to a convoy bound for Greece, one Savoia-Marchetti SM.79 medium bomber was shot down on 29 July by Eagle's Sea Gladiators while attacking the fleet.

[41] On 22 August three Swordfish from 824 Squadron, flying from Sidi Barrani, attacked and sank the Italian submarine Iride and the depot ship Monte Gargano in the Gulf of Bomba.

[50] Eagle spent most of December in Alexandria, but her aircraft supported the ground war, most notably when they spotted for the battleships Warspite and Barham during the bombardment of Bardia on 2 January 1941.

In mid-January, the ship covered a convoy to Greece, but bad weather foiled plans to attack Italian bases en route.

When Eagle was covering another convoy to Malta in mid-February, the ship carried nine Fairey Fulmars of 805 Squadron, five Sea Gladiators and six Swordfish.

[51] After the carrier Formidable arrived on 9 March to relieve Illustrious, orders were cancelled that would have transferred Eagle to the South Atlantic to hunt for German commerce raiders and the ship did not leave Alexandria until 9 April.

The ship's oil fuel capacity was reduced to 2,990 long tons (3,040 t) in exchange for an increase in her petrol storage of 3,000 imperial gallons (14,000 L; 3,600 US gal).

For the next operation on 17 May, the Swordfish and Sea Hurricanes of 813 Squadron flew back on board to join the 17 Spitfires and six Fairey Albacore torpedo bombers destined for Malta.

[70] The escorts reached Gibraltar on 17 June and did not make the next delivery of aircraft until 14 July when 32 Spitfires were flown off to Malta (Operation Pinpoint).

[73] On the early afternoon of 11 August, Eagle was hit by four torpedoes from the German submarine U-73, commanded by Helmut Rosenbaum, and sank within four minutes, 70 nautical miles (130 km; 81 mi) south of Cape Salinas at position 38°3′0″N 3°1′12″E / 38.05000°N 3.02000°E / 38.05000; 3.02000; Cape Salinas is the southernmost point of Majorca (that is, approximately midway between Palma, Majorca and Algiers, Algeria.)