Completed in 1944, her aircraft made several attacks that year against the German battleship Tirpitz, inflicting only light damage; they also raided targets in Norway.

The ship was transferred to the British Pacific Fleet (BPF) at the end of the year and attacked Japanese-controlled oil refineries in Sumatra in January 1945 before joining the American forces in March as they prepared to invade the island of Okinawa in Operation Iceberg.

After returning to the UK in early 1946, Indefatigable was modified for transport duties, and ferried troops and civilians for the rest of the year before she was reduced to reserve.

The Implacable class were ordered under the 1938 Naval Programme by the Chamberlain government as part of the general rearmament begun in response to the rise of Nazi Germany and Fascist Italy.

To remain within the 23,000 long tons (23,000 t) limit allowed by the Second London Naval Treaty, these improvements could only be made by reducing armour protection.

[8] The turbines were designed to produce a total of 148,000 shaft horsepower (110,000 kW), enough to give the Indefatigable-class ships a maximum speed of 32.5 knots (60.2 km/h; 37.4 mph).

[11] The ship's main armament consisted of sixteen quick-firing (QF) 4.5-inch (114 mm) dual-purpose guns in eight twin-gun turrets, four in sponsons on each side of the hull.

[22] While fitting out, in order to confound the enemy, a ruse known as Operation Bijou, initiated by London Controlling Section, was launched whereby it was made known that Indefatigable had already entered service.

[23] The ship was commissioned on 8 December 1943[22] and began sea trials, which revealed many problems that required rectification and delayed her formal completion until 3 May 1944.

[24] Indefatigable's first mission was a brief sortie on 1 July 1944 to provide air cover for the ocean liner RMS Queen Elizabeth that was ferrying American troops to Britain.

[29] Indefatigable and several escort carriers attacked targets in Norway on 10 August, destroying 6 Messerschmitt Bf 110 fighters and sinking a minesweeper.

[31] The first mission took place on the morning of 22 August when Indefatigable launched 12 Barracudas, 11 Fireflies, 8 Hellcats, and 8 Seafires against the German battleship and nearby targets.

She became the flagship of the 1st Aircraft Carrier Squadron (1st ACS) when Rear Admiral Sir Philip Vian hoisted his flag on 15 November.

Their aircraft, 40 Seafires, 12 Fireflies, and 21 Grumman TBF Avenger torpedo bombers, followed on 19 November, and she sailed for the Far East to join the British Pacific Fleet.

[38] Together with Victorious and Indomitable, Indefatigable attacked an oil refinery at Pangkalan Brandan, Sumatra on 4 January 1945 (Operation Lentil).

The ship's Seafires lacked the range to reach the targets so they were retained on combat air patrols (CAP) over the fleet for both attacks.

She contributed 10 of her Avengers and all of her Fireflies to the first attack, which destroyed most of the oil storage tanks and cut the refinery's output by half for three months.

Her Seafires shot down a Mitsubishi Ki-46 "Dinah" reconnaissance aircraft searching for the fleet and 5 Kawasaki Ki-48 "Lily" bombers that attacked at low level.

Their short range and lack of endurance was considered by Vian to be a severe handicap for the BPF, which returned to action on 4 May and again attacked targets in the Sakishima Islands.

Statistics compiled by the BPF staff showed that 61 Seafires were lost or damaged beyond repair during both phases of the operation due to deck-landing accidents.

A combination of bad weather, refuelling requirements and the atomic bombing of Hiroshima delayed the resumption of air operations until 9 August.

The first airstrike was tasked to attack Kisarazu Air Field with four Fireflies and six Avengers, escorted by eight Seafires, but was forced to divert to its secondary target because of bad weather.

[50] After the ceasefire, Indefatigable's aircraft continued to fly CAP and flew reconnaissance missions looking for Allied prisoners of war, dropping supplies to them as they were located.

Her hangars were modified to accommodate over 1,900 passengers, including women, and she departed for Australia on 25 April carrying 782 RN personnel and 130 Australian war brides.

Two days later Captain Robert Sherbrooke, VC, relieved Grindle and Indefatigable began her sea trials on 28 June.

She was inspected by Rear Admiral St John Micklethwaithe, Flag Officer Training Squadron, on 3 July and received her first trainees shortly afterwards.

Captain John Grant relieved Sherbrooke on 6 June and the ship was opened to visitors as part of the Festival of Britain on 17 July.

Rear Admiral Royer Dick hoisted his flag aboard the carrier in September until she began a short refit at Devonport in January 1952.

Captain Ralph Fisher assumed command on 30 January 1953 and took her to sea three weeks later for exercises with the Home Fleet and her annual visit to Gibraltar.

In August she began transferring her training duties to the carrier Ocean and arrived at Rosyth on 2 September to be paid off, a process that took until the following month to complete.