Prior to the attack on Pearl Harbour in 1941, what was the US Navy policy regarding the use of aircraft carriers?

by abh0rsen

As I understand it, prior to the attack, there were 3 main naval powers employing aircraft carriers: Britain, the USA and Japan.

British doctrine was to use carrier borne aircraft as support for their battle groups. Battleships remained the core of the force while planes were used for reconnaissance, anti-submarine patrols and harassing enemy task forces. The aircraft were not intended to be the main strike force of the fleet. As far as I know, British carriers could not carry the same number of aircraft as their Japanese or American counterparts. They were also equipped with antiquated bi-planes rather than modern aircraft. Despite this, the effectiveness of aircraft attacking ships was demonstrated by the contributions to the hunt for the Bismarck and the attack on the Italian naval base at Taranto. This attack by a single carrier and 30 bi-planes put half the battleships of the Italian Navy out of commission for several months at least.

The Japanese approach seemed to be the reverse of the British. Carriers became the core of the fleet and battleships were relegated to escorting carriers and supporting land assaults with their big guns. Though numerically superior at the outset of conflict, the Japanese fleet was hopelessly outmatched in a protracted struggle with the USA. It seems that the combination of the British success at Taranto, the need for a crippling strike on the US Pacific Fleet and the visionary leaders available to the IJN led to aircraft carriers becoming the cutting edge of the Japanese Navy.

The USA was clearly interested in the use of aircraft carriers judging by the number and quality of the ships in service in 1941. After the attack, the USA appeared to follow the Japanese model of organising task forces around carriers. However, the attitude of the Navy regarding the use of these ships before the attack is a mystery to me. Was the US Navy operating under the British idea of using carriers to support traditional battle fleets? Or were they already leaning towards the idea of carriers becoming the dominant ships of the fleet and had this thought dramatically underlined in December 1941?

thefourthmaninaboat

Your question has several misunderstandings about carrier doctrine in the world's major navies in the 1930s and early 1940s. All three navies saw the carrier as operating as a supporting part of the battlefleet, rather than as the most important part of the fleet in its own right. However, there were clear differences in how they operated.

The Royal Navy had experimented with carrier-centric doctrines during exercises in the late 1920s and early 1930s. From 1929, the Mediterranean Fleet had exercised with the three carriers, Courageous, Glorious and Furious, acting together. These exercises clearly showed that carriers were more effective working together. While the RN planned to operate carriers together, it never fully developed the combined strike doctrine that the IJN did. Instead, the air groups of these carriers would operate more autonomously. The exercises of the 1920s-30s clearly showed the capability of the carrier. Equally, they were seen as being limited by the performance of available aircraft, and by the numbers of available carriers. They were also seen as being vulnerable in the event of a surface action, especially at night or in bad weather. To this end, carriers were seen as an essential part of a combined-arms tactical system. The RN's battle-fleet doctrine of 1939, as laid down in the 1939 'Fighting Instructions', assigned the carrier four main roles: finding the enemy fleet, sinking the enemy's carriers, to slow and damage the enemy battlefleet, and to observe the fall of shot for the battleships. Carrier aircraft were also seen as significant for anti-submarine work. The carriers were to be concentrated in a single force, along with the rest of the battlefleet. The carriers would protect the battleships from air attack, while the battleships protected the carriers from surface attack. The carriers would also benefit from the additional anti-aircraft umbrella provided by the battleships. However, the need for the whole force to manoeuvre as one slowed down the tempo of carrier operations. Once the enemy carrier force had been defeated, and their battlefleet slowed by carrier attacks, the British battlefleet would seek to fight a surface action. Once it had closed with the enemy, the carriers would drop out of the combined force. The battleships were to close to ~15,000 yards, and then engage by divisions, rather than in line as it had during WWI. The RN wanted to fight at night, at relatively short ranges, and to this end, the Fleet Air Arm (uniquely) developed a night-strike capability.

The Japanese doctrine, like the British, saw the primary role of the carrier as destroying the enemy's carriers, and then harassing his battlefleet, as part of a combined-arms fleet. However, they saw the operations of this combined-arms fleet somewhat differently. During the 1930s, the IJN mostly expected their carrier force to operate in widely separated groups, aiming to surround the enemy fleet. However, as time moved on, they realised that this made the carriers vulnerable to air attack, and concentrated them into a single group, starting in 1940. This was to operate ahead of the main battlefleet, rather than with it as the British equivalent would. This allowed the carriers to manoeuvre as needed to launch aircraft, without having to drag the rest of the battlefleet along with them. The ideal Japanese battle would start with the Japanese submarine screen spotting the enemy fleet. The enemy fleet would then be worn down by submarine, air and night torpedo attacks. Once contact with the enemy battlefleet was made, the Japanese battleships would fight a long-range gunnery duel (ranges of 35,000 yards or more), before closing to a 'decisive range' of 19-22,000 yards to finish the enemy off.

American carrier doctrine strongly resembled the pre-1940 Japanese doctrine. The carriers, rather than operating with the battle-fleet, operated semi-autonomously. They formed, along with heavy cruisers and destroyers, as a scouting force. Carriers did not generally operate together, but operated independently, spread widely over a large area. Once again, the role of the carriers was to scout, to win air superiority by sinking the opposing carriers, and to harass the enemy battlefleet. Exercises carried out in the 1930s were seen as showing that combined-arms attacks were the right way to use carriers. They suggested that carrier attacks at the start of a battlefleet engagement would both greatly increase the effect of the carrier attacks and the battlefleet's own fire, as the enemy could not easily respond to both. The American battlefleet was intended to fight at 30,000 yards or more, operating in line astern. It also developed special tactics to counter the Japanese (and British) battlecruisers, which could use their superior speed to 'cross the T' of the American line. It was only as the Essex class began to roll off the slipways, the USN became more able to switch to a carrier-centred doctrine. Once they could gather enough carriers to operate a massed 'alpha strike', the battleship was no longer needed as the primary surface combatant.

It should be clear from the above that the three main navies saw the carrier fitting a similar, subsidiary role. The main difference was that the British doctrine saw the carrier operating as part of a combined-arms force, while the Americans and Japanese saw it as part of a more autonomous unit. But why did they hold to this doctrine? Sumida argues cogently that the carrier was, before 1940-41, the carrier was not, on its own, a decisive weapon. To see why, we can look at the strike aircraft they carried. The RN was, in 1939, operating the biplane Swordfish torpedo bomber, and the underpowered Skua dive-bomber. The IJN had the D1A Susie for dive-bombing (with the Val just about to enter service), though the B5N Kate was an excellent torpedo bomber. The USN was operating the biplane SBC Helldiver, and the TBD Devastator. With the notable exception of the Kate, all of these aircraft were slow, vulnerable, and had comparably limited ranges and payloads. Until the carrier had more effective aircraft, it could not be a decisive tool. Additionally, relatively few of these aircraft could be deployed - until carriers like Hornet or Zuikaku entered service in 1940-41, carrier fleets were comparatively small. As such, the belief that the carrier could only play a subsidiary role was justified. It was not that admirals did not understand the carrier. Rather, the carrier could not meet the expectations that its later effectiveness would place upon it.

While the carrier was not, for much of the war, at the centre of naval doctrine in any navy, it could still decide battles. Note that all the doctrines above assumed, as an early step, that friendly carriers would destroy the opposing carriers, ensuring air superiority. For the Americans and Japanese navies, which required aerial spotting to fight at the long ranges they planned for, aerial supremacy was all but required. As a result, whichever side lost the carrier duel would tend to withdraw, rather than closing to engage in a surface action on its enemy's terms. Midway is a clear example of this - while the IJN had supremacy in terms of surface ships, once they lost their carriers, they chose to withdraw with their battle-fleet. This state of affairs dominated while neither side had sufficient carriers and aircraft to destroy both the enemy's carriers and its battleships in rapid succession. Once this was achieved, the carrier could, and did, become the primary element of the fleet. Another way the carrier could influence naval operations before it achieved dominance was by providing a protective air umbrella under which battleships could operate in areas where enemy land-based air prevailed. British operations in the Mediterranean are clear examples of this, as are the naval battles off Guadalcanal or Leyte Gulf - without the fact that control of the air was disputed between Japanese and American aviation, neither of these campaigns could take place.

Sources:

Building a Doctrine: U. S. Naval Tactics and Battle Plans in the Interwar Period, Trent Hone, International Journal of Naval History, Vol. 1, No. 2, October 2002

The Evolution of Fleet Tactical Doctrine in the U.S. Navy, 1922-1941, Trent Hone, The Journal of Military History Vol. 67, No. 4, October 2003

In Support of the Battle Line: Gunnery's Influence on the Development of Carrier Aviation in the U.S. Navy, Thomas Wildenberg, The Journal of Military History Vol. 65, No. 3, July 2001

Royal Navy Fleet Tactics on the Eve of the Second World War, James P. Levy, War in History, Vol.19 No. 3, 2012

'The Best Laid Plans': The Development of British Battle-Fleet Tactics, 1919-1942, Jon Tetsuro Sumida, The International History Review, Vol. 14, No. 4, 1992

Kaigun: Strategy, Tactics and Technology in the Imperial Japanese Navy 1887-1941, David C. Evans and Mark R. Peattie, Naval Institute Press, 1997

Royal Navy Strategy in the Far East, 1919–1939: Planning for a War against Japan, Andrew Field, Frank Cass, 2004