Formidable's aircraft played a key role in the Battle of Cape Matapan in early 1941, and they subsequently provided cover for Allied ships and attacked Axis forces until their carrier was badly damaged by German dive bombers in May.

She was subsequently assigned to the British Pacific Fleet (BPF) in 1945 where she played a supporting role during the Battle of Okinawa and later attacked targets in the Japanese Home Islands.

Admiral Sir Reginald Henderson, Third Sea Lord and Controller of the Navy, was determined not to simply modify the previous unarmoured Ark Royal design.

This halved the aircraft capacity of the Illustrious class compared with the older unarmoured carriers, trading offensive potential for defensive survivability.

[7] She carried a maximum of 4,850 long tons (4,930 t) of fuel oil, which gave her a range of 10,700 nautical miles (19,800 km; 12,300 mi) at 10 knots (19 km/h; 12 mph).

[9] The ship's main armament consisted of sixteen quick-firing (QF) 4.5-inch (110 mm) dual-purpose guns in eight twin-gun turrets that were mounted in sponsons on the side of the hull.

[12] While under repair in late 1941, Formidable's light AA armament was augmented by the addition of 10 Oerlikon 20 mm autocannon in single mounts[13] with a maximum range of 4,800 yards (4,400 m).

The hangar deck itself was 2.5 inches (64 mm) thick and extended the full width of the ship to meet the top of the 4.5-inch waterline armour belt.

Four days later the ship was ordered north to replace her sister Illustrious with the Mediterranean Fleet after she had been badly damaged by German dive bombers.

On the morning of 27 March, major elements of the Italian Fleet were spotted en route to the sea lanes between Egypt and Greece and the carrier sailed later that afternoon with a force of three battleships, cruisers and destroyers under the command of Admiral Sir Andrew Cunningham.

[29] On 18 April the Mediterranean Fleet sortied to bombard the primary Axis supply port of Tripoli and was attacked by a pair of SM.79 torpedo bombers from Rhodes.

At 13:10 a formation of Junkers Ju 87 Stuka dive bombers was spotted from II./StG 2; based in Cyrenaica; they were searching for supply ships bound for Tobruk and not involved in the Battle of Crete.

The pair of Fulmars on Combat Air Patrol (CAP) shot down one of the Stukas after it had dropped its bomb and were able to land aboard shortly afterwards but take-offs could not be made until 18:00.

[34] Formidable sailed on 17 February to join the Eastern Fleet in the Indian Ocean, escorting a convoy to Freetown, Sierra Leone, en route.

Two days after Formidable's arrival, the Japanese First Air Fleet departed from Celebes (Sulawesi) in the Dutch East Indies to attack British forces in the Indian Ocean.

Force A, consisting of Formidable, her sister Indomitable and Warspite, was ordered to Addu Atoll to refuel on 3 April after the Japanese failed to attack as the British expected.

Force A refuelled at Addu Atoll on 9 April and was then ordered to Bombay to calm fears of a Japanese attack on India's west coast.

She remained off the Algerian coast providing air support for Allied forces for the rest of the month, and one of her Seafires shot down a Ju 88 on 28 November.

[40] Formidable was the only carrier in the Mediterranean after Torch until she was joined by Indomitable in mid-June 1943 as part of the buildup for the Allied invasion of Sicily (Operation Husky).

[Note 3] The fighters aboard the smaller carriers protecting the forces ashore suffered heavy attrition during the early days of the operation and Formidable transferred 2 Seafires and 15 Martlets to Unicorn as replacements for their losses.

She arrived in Sydney, the BPF's main base, on 10 March after several stops en route to refuel and embark stores and ammunition.

Formidable was called forward six days later to join the 1st Aircraft Carrier Squadron (1st ACS) of the BPF on operations[54] as a replacement for Illustrious, which was in poor mechanical shape.

They detached King George V and Howe, as well as five cruisers, that morning to bombard Nobara and Hirara airfields of Miyako Island while fighters flew a protective CAP over them and spotted the fall of their shells.

The carrier had just launched two Corsairs for bombardment-spotting duties and the deck park of eleven Avengers was being moved forward to allow aircraft to land when an undetected Mitsubishi A6M Zero fighter attacked at 11:31.

The fragment severed the steam pipes in the centre boiler room and forced its evacuation, cutting the ship's speed to 14 knots (26 km/h; 16 mph).

The dent was filled by wood and concrete and covered by thin steel plates tack-welded to the deck so that she was able to operate aircraft by 17:00 and steam at a speed of 24 knots (44 km/h; 28 mph).

Rawlings decided to immediately withdraw to give Victorious and Formidable more time to make repairs and to replenish their depleted air groups.

A second fighter sweep, led by Lieutenant Robert Hampton Gray, RCNVR, senior pilot of 1841 NAS, was diverted to attack Japanese warships located in Onagawa Wan, Miyagi Prefecture, with his eight Corsairs.

[73] Vice-Admiral Vian addressed the ship's crew on 27 December before she departed the following day with 800 naval personnel embarked for passage home.

She was paid off on 12 August and a later survey revealed that her wartime damage and poor material shape meant the ship was beyond economical repair at a time when money was very tight.