The carriers were critical for the hunter killer naval groups that knocked out the U-Boat wolfpacks.
Correct!
Before Dec. 1941 the Allies=UK were aware of the need and usefulness of carrier borne aircraft to provide U-boat protection for the Atlantic convoys. Escort carriers (CVE) are the designs eventually settled upon for that task as well as for the Hunter-Killer Groups.
...
The Royal Navy had recognized a need for carriers to defend its trade routes in the 1930s.
[1] While designs had been prepared for "trade protection carriers" and five suitable liners identified for conversion, nothing further was done mostly because there were insufficient aircraft for even the fleet carriers under construction at the time. However, by 1940 the need had become urgent and
HMS Audacity was converted from the captured German merchant ship MV
Hannover and commissioned in July 1941.
[2] For defense from German aircraft, convoys were supplied first with
fighter catapult ships and
CAM ships that could carry a single (disposable) fighter. In the interim, before escort carriers could be supplied, they also brought in
merchant aircraft carriers that could operate four aircraft.
In 1940, U.S. Admiral
William Halsey recommended construction of naval auxiliaries for pilot training.
[3] In early 1941 the British asked the U.S. to build on their behalf six carriers of an improved
Audacity design, but the U.S. had already begun their own escort carrier.
[4] On 1 February 1941, the United States Chief of Naval Operations gave priority to construction of naval auxiliaries for aircraft transport.
[5] U.S. ships built to meet these needs were initially referred to as
auxiliary aircraft escort vessels (
AVG) in February 1942 and then
auxiliary aircraft carrier (
ACV) on 5 August 1942.
[6] The first U.S. example of the type was
USS Long Island.
Operation Torch and North Atlantic anti-submarine warfare proved these ships capable aircraft carriers for ship formations moving at the speed of trade or amphibious invasion convoys. U.S. classification revision to
escort aircraft carrier (
CVE) on 15 July 1943 reflected upgraded status from auxiliary to combatant.
[7] They were informally known as "Jeep carriers" or "baby flattops". It was quickly found that the escort carriers had better performance than light carriers, which tended to pitch badly in moderate to high seas. The
Commencement Bay class was designed to incorporate the best features of American CVLs on a more stable hull with a less expensive propulsion system.
...
en.wikipedia.org
Also, aircraft carriers had proven a value for fleet engagements long before Dec. 1941. The Swordfish (Stringbag) torpedo aircraft from USN carriers had damaged the German battleship Bismark, jamming it's rudder, such that it could be found and sunk by the fleet cruisers and battleships (April 1941).
Prior to that was the Battle of Taranto, which could be consider the "inspiration" for Japan's Pearl Harbor attack.
...
The
Battle of Taranto took place on the night of 11/12 November 1940 during the
Second World War between British naval forces, under Admiral
Andrew Cunningham, and Italian naval forces, under Admiral
Inigo Campioni. The
Royal Navy launched the first all-aircraft ship-to-ship naval attack in history, employing 21
Fairey Swordfish biplane
torpedo bombers from the
aircraft carrier HMS Illustrious in the
Mediterranean Sea.
The attack struck the battle fleet of the
Regia Marina at anchor in the harbour of
Taranto, using
aerial torpedoes despite the shallowness of the water. The success of this attack augured the ascendancy of
naval aviation over the big guns of
battleships. According to Admiral Cunningham, "Taranto, and the night of 11–12 November 1940, should be remembered forever as having shown once and for all that in the
Fleet Air Arm the Navy has its most devastating weapon."
[1]
...
en.wikipedia.org
Carriers also played a valuable early war rolle in escorting convoys to Malta and as 'ferry' for fighters to fly off to Malta. And there were a couple of other naval engagements during the early ETO where the absence of carriers proved detrimental to Allied outcome.