Aircraft Carrier Tactics of World War II
There was a great transformation in aircraft carrier tactics beginning in August 1942. Although naval warfare naturally favors the attack, in just a short time new weapons and technology radically improved the power of the defense. By 1944, US Navy carriers were seriously threatened only by kamikazes, essentially human-guided missiles, and even they failed to sink a single large American carrier.
Aircraft carriers were first developed in the 1920s. In the years before World War II, there were two main schools of thought about naval aviation. The first was that carrier based planes would scout for the main battleship fleet, soften up the enemy fleet, and spot for the big guns of the battleships. Although it is now easy to see the flaws in this theory, at the time the vast majority of the navy's firepower came from its guns, with long range aerial ordnance accounting for only a small fraction of the total. The second theory, a relatively radical one, was that carrier aircraft would destroy everything afloat. (Hughes 88) Both of these theories proved to be extreme.
When World War II broke out in 1939, little was learned about carrier tactics because Germany and Italy had no carriers to fight with. When the war with Japan started in December 1941, both Japan and the United States had little idea how the war would be fought.
Japanese carriers made air strikes on US bases in late 1941, but it took until 1942 for combat between carriers. In 1942, carrier forces were split so that each carrier was escorted by approximately two cruisers and three destroyers. (Wukovits 39) These escorts surrounded the carrier at a distance in a circular "wagon wheel" formation. If the force needed to change direction, each ship would turn to the proper heading, maintaining the circular formation. This screen of escorts protected the valuable carrier with anti-aircraft fire. It would also fight off any surface ships which reached the task force and protect the carrier from submarine attack. (Hughes 88-90) The ships were manufactured so that their speeds were roughly comparable, and a carrier group could travel at about 30 knots.
In 1942, naval aviators believed that an air strike from one carrier could sink two to three enemy carriers. Anti-aircraft defenses were weak. Because of this, carriers were dispersed in the theory that if the enemy could only find one carrier, they could only sink one carrier. Massing all the carriers in one screen would endanger them all unnecessarily. (Hughes 103) The US Navy kept their carriers within supporting distance. At Midway, the two carrier task forces were kept 25 miles apart - far enough away to make it unlikely that they would be be detected by the same scout plane, but close enough so that each group's fighter screen could support the other. (Lundstrum 323) In contrast, the Japanese would sometimes spread their carrier task forces out over vast stretches of ocean.
Battleships were still a great danger to the carrier task force. At night, it was impossible for a carrier group to detect a force of battleships. Within the period of one night, a force of battleships could traverse the 200 mile range of aircraft and be within gun range of the carrier task force before morning. (Hughes 105) Even in daylight, where carriers were often forced to turn into the wind to launch and land planes, the threat from battleships was all too real. The decisive battle of Midway could have been very different had the Japanese deployed their numerically superior battleships in the front, and not in the rear, of their naval force. Still seeing the carriers as scouts for the battleships, however, their battleships would not enter the fray. On both sides, however, submarines were seen as important screening vessels for the carrier fleet. In several battles subs were able to sink enemy carriers, and they were always useful in recovering downed airmen.
Carrier based planes were of three types: torpedo bombers, dive bombers, and fighters. Torpedo bombers carried a single torpedo which was dropped and propelled itself toward the target. Dive bombers flew directly over the target, made a steep dive toward the target and released a bomb, then pulled out of the dive. In 1942, the United States used the Devastator torpedo bomber, which was being replaced by the Avenger torpedo bomber. (Reynolds 145) The Dauntless dive bomber could carry 1,200 pounds of bombs. (Reynolds 79) The Wildcat fighter was inferior to the Japanese Zero fighter. It was slower, had a shorter range, and couldn't climb as fast. (Reynolds 81) Due to this inferiority, the Americans developed a tactic called the Thach Weave in which two Wildcats flew in formation. If a Zero followed one of the fighters, the Wildcats weaved in and out so that one fighter could get a crossfire on the Zero. (Reynolds 64-5)
|Each US carrier had an air wing of 94 planes. In light of the theories of the strength of the attack, only 25% of these planes were fighters, which intercepted enemy search planes and air strikes and escorted the dive bombers and torpedo bombers on strike missions. The remaining 75% of the air wing were dive bombers and torpedo bombers. (Hughes 102) Since attacking the enemy before he attacked you was of such great importance, the carrier force had to locate the enemy by scouting. At the first carrier battle, Coral Sea, scouting was poorly done by both sides. American scouting was conducted by the Dauntless dive bomber. Instead of using valuable carrier aircraft, the Japanese often used float planes from battleships and cruiser, an economy measure which didn't always work out as the float planes proved to be inferior to carrier planes as scouts.||
Model of Yamato Class Battleship - note float planes and hanger
As there was no advantage to remaining on the defense, when the enemy was located, an air strike was usually made. The maximum range for an air strike with dive bombers and torpedo bombers was about 200 miles. These planes were escorted by fighters, but only 25% of a carrier's planes were fighters and some would be retained to protect the fleet. For example, in March 1942 two US carriers made a strike on Japanese ships conducting the invasion of New Guinea. The strike was composed of 48 dive bombers, 25 torpedo bombers, and 18 fighters. Fifteen planes were retained to protect the carriers. (Cressman 41) At Coral Sea, two American carriers sent 54 dive bombers, 21 torpedo bombers, and 24 fighters to strike the Japanese fleet. Forty-three planes were lost out of 99 planes, but a Japanese carrier was sunk. The Japanese sank an American carrier with a force of 69 planes. (Wukovits 37) At Midway, three American carriers sank four Japanese carriers at a cost of one carrier lost. In one instance, an American torpedo bomber force attacked the Japanese without fighter escort and was nearly annihilated, and on the whole casualties were high. In the whole battle, 126 American planes survived out of 233 planes, a 46% loss rate, and no Japanese planes survived out of 272. (Hughes 97) While making attacks, planes often came from the direction of the sun to make anti-aircraft fire less effective.
Lacking radar early in the war, the Japanese were forced to use their fighter aircraft on combat air patrol, or CAP, to detect incoming enemy search planes and air strikes. This inefficient method could easily fail, especially in cloudy weather, and it meant that the fighters were spread out and not concentrated for an organized defense when an enemy airstrike arrived. With just a five mile visual range, there was little time to come to react. In contrast, American radar gave warning of enemy aircraft out to 80 miles. (Lundstrum 89-91, 228) Although radar was a big advantage, early on American CAP planes were frequently sent to confront friendly approaching aircraft which did not have Identification - Friend or Foe (or IFF) gear. On at least one occasion, Japanese planes were allowed to approach in the confusion. (Lundstrum 73) For the slow climbing Wildcats, an altitude advantage in dogfights was critical. CAP was usually deployed on at least two different altitudes because attackers approached at high and low levels, and it was impractical for a high altitude fighter to intercept low level enemy planes then return to high altitude. Good coordination was important too, with an interception best as far from the carrier as possible, 30 miles or so, to give the fighters maximum time to disrupt the enemy formation, preferably meeting it before the dive and torpedo bombers split up. (Lundstrum 304, 443)
Forming and escorting a strike was also a difficult proposition. The first option was a "normal departure" in which squadrons organized but the whole group didn't. This could lead to a relatively quick but confused attack. The second option was "deferred departure" in which the whole group organized. This allowed for maximum striking power and protection, but its time consuming nature limited the range of the airstrike. Escorting fighter typically would fly above and somewhat behind the attack planes. Since dive bombers were at a low altitude after their attack, and since torpedo bombers attacked at a lower altitude to begin with, two levels of fighter escort were required. (Lundstrum 194)
Early in the war ship losses were also high. In the beginning of 1942, Japan had 10 carriers to America's 4. (Reynolds 63) By August 1942, Japan had 4 carriers to oppose only one American carrier. (Reynolds 121) But by August 1942, carrier warfare began to change. Before the war, the United States started production of 24 new large Essex carriers, 9 smaller Independence class carriers, and an even greater number of small, slow escort carriers which were used to support ground operations and provide anti-submarine escort, among other duties. (Reynolds 132) In 1943, the new American carriers began to enter service, and due to factors detailed below, none of the new Essex class carriers were sunk, even to kamikaze attacks late in the war. Starting in August 1942, new fast battleships were attached to carrier forces. They were used to bombard shore positions, provide anti-aircraft protection, and were detached at night to protect against the enemy fleet. New cruisers were made that were especially designed as anti-aircraft gun platforms. (Hughes 105)
For the November 1943 raid on Rabaul, just over half of the task force's planes were fighters. (Morison, Breaking 331) In 1944, 65% of US Navy air wings were fighters as opposed to 25% in 1942. The Japanese, however, had only 34% fighters. (Hughes 102) The increased number of American fighter planes better allowed a multi-level, or stacked, CAP, which hadn't been as practical early in th ewar. (Lundstrum 443) New planes also changed carrier warfare. In 1943, the Japanese introduced a new dive bomber, but it could carry only 1,000 pounds of bombs, little different from past models, and in 1944 the Japanese introduced a new torpedo bomber which flew at 300 mph. American improvements were much more impressive. In 1943, the US introduced the Helldiver dive bomber, capable of carrying 2,000 pounds of bombs, twice that of the Japanese dive bomber. In 1944, the US introduced the much superior Hellcat fighter with a range of 1,300 miles, much better than the 770 mile range of the Wildcat that it replaced. It could also be fitted with bombs and sent on airstrikes after air superiority was achieved. Also new was the Corsair fighter-bomber which could reach 417 mph and could be equipped with rockets and bombs to support amphibious operations. (Reynolds 145-9) Perhaps as important, the US Navy had a vast supply of well trained new pilots while the Japanese never adequately replaced the excellent pilots they lost early in the war. Facing inadequate pilots, only 270 Hellcats were lost as they dispatched over 6,000 Japanese planes. (Dunnigan 218)
|Vought F4 Corsair - intend to replace the Wildcat, the project was delayed, so the F6 Hellcat instead became the standard fighter plane on carriers. Due to the large prop, the wings were shaped to raise the fuselage. The position of the cockpit made carrier landings difficult.|
|F6 Hellcat - Originally designed as an improved version of the Wildcat, the plane was in fact a vast improvement. When not needed as fighters, the planes could be armed with 500 pound bombs.|
|Lunga Point Class Escort Carrier - Small carriers like these, with only 27 aircraft, helped transfer aircraft and performed escort duties, freeing up larger carriers for more important duties.|
In 1944, the Japanese could scout to a range of 560 miles and attack at a range of 400 miles. In comparison, the US Navy could scout out to just 350 miles and attack to around 200 miles. (Reynolds 139) Earlier in the war this could have resulted in a decisive Japanese victory, but this American deficiency was largely negated by increased defensive abilities and technologies, not the least of which was the new invention of radar. Radar had many uses and was vitally important in carrier warfare. At Midway, because the Japanese lacked radar, their carriers were crammed with planes refueling and rearming when the decisive American airstrike arrived, leaving them extremely vulnerable at the worst possible time. As we have seen, in addition to detecting attacking enemy aircraft, radar directed intercepting aircraft and anti-aircraft fire and could even locate the enemy fleet. (Hughes 116)
Radar was also fitted on 5 inch anti-aircraft shells used for long range anti-aircraft fire. These proximity fuse shells exploded when near the target, instead of at a specific set time with previous fuses, which vastly improved the effectiveness of the guns. (Hughes 116,132) The Bureau of Ordnance estimated that guns firing proximity rounds were four times more effective than guns firing regular time-fused rounds and had an advantage of 8.1 to 3 over the 40mm weapon. (Rowland 286-7) The proximity fuze's performance in battle was impressive. Soon after their introduction, an American task force reported that it downed 91 planes of a 130 plane Japanese formation. (Rowland 287)
For medium range anti-aircraft duty, a quick firing Bofors 40 mm gun with exploding shells was adopted. These guns were later tied in with the fire control system used for 5 inch guns, bringing improvement to both gun types. (Rowland 386) Late in the war, half of all downed aircraft were shot down by the 40mm guns. (Rowland 234) For close-in anti-aircraft protection the newly adopted 20mm Oerlikon gun was 8 to 10 times more effective than the .50 caliber machine gun that it replaced. (Rowland 235) Up until September 1944, 20mm guns accounted for 32% of downed aircraft. New gyroscopic optical fire controllers which calculated a target's rate of change helped make the guns more effective than when used with a standard sight over the gun barrel. Improved fire control systems made AA weapons much more effective. An early indication of this was in October 1942 when the battleship South Dakota shot down ALL 38 planes of an attacking Japanese force. Electrical, as opposed to mechanical fire control computers were developed, and further improvements included the connection of fire control to the ship's radar equipment. This allowed "blind firing" at targets approaching from the sun, a favorite tactic of the time, and at night. (Rowland 382, 392)
Anti-aircraft protection increased not just because of the new proximity fuses and the improved QUALITY of the guns and fire control. The QUANTITY of anti-aircraft guns was drastically increased also. The battleship Nevada, an old Pearl Harbor survivor is a good example. It's 5 inch gun armament was doubled from 8 to 16 guns, its four 3 inch guns were replaced by eight 40 mm quad mounts with a total of 32 gun barrels, and its eight .50 caliber machine guns were replaced by forty 20 mm guns. The battleship South Dakota completed during the war is another example. Originally designed to have three 1.1 inch quad mounts, by March 1945 there were instead seventeen 40 mm quad mounts. Instead of its planned twelve .50 caliber machine guns, in March 1945 there were no less than seventy seven 20 mm guns! (Rowland 243, 246) Ships were crammed with so many anti-aircraft weapons that it became impossible to use each of these weapons up to its potential. The improved anti-aircraft defenses could even deal with the kamikaze threat of 1945.
USS Texas pre-war - Note the relative lack of anti-aircraft weapons.
USS Maryland - This brass model gives some idea of the degree to which pre-war battleships were modified with massive additions of AA weapons.
|USS Missouri - Battleships built during the war entered the conflict with many more AA weapons than they were originally designed for.|
Due to increased anti-aircraft capability and the greater numbers of carriers available, a new method of forming carrier task groups was necessary. In the Fifth Fleet, there were now 15 carriers. It would have been impossible to control 15 carriers if each had its own protective screen, but this was now unnecessary. Therefore, task groups consisted of four carriers protected by three to five cruisers and twelve to fourteen destroyers. With this method, there were only four separate carrier groups, making the entire carrier force much easier to control while the effective anti-aircraft protection made them safe from enemy attack. It was more difficult to coordinate the air power from within a four carrier task force, which resulted in somewhat clumsy air operations, but the increased defensive power made this a worthy tradeoff. The Japanese had fewer carriers, lacked escorting ships, and had not significantly improved their anti-aircraft defense. Unlike the US fleet, the major Japanese warships were often kept separate from the carriers specifically for use in surface actions, so their anti-aircraft firepower wasn't available to protect the carriers. Therefore, the Japanese provided a screen of 12 less effective escorts to a group of two carriers. (Macintyre 255-6)
The battles of the Philippines Sea in June 1944 and Leyte Gulf in October 1944 destroyed Japanese naval aviation. Even by the Philippines Sea battle the US fleet could fight more conservatively and be satisfied with destroying Japanese naval air power and protecting the beachhead without actually sinking Japanese carriers. At Leyte Gulf Admiral Halsey failed to realize this and allowed himself to be lured away from protecting the vulnerable troops transports. Although the Japanese carriers were destroyed, they were nearly impotent sacrificial bait. For the Americans, disaster was narrowly averted at the beachhead. With the Japanese carrier threat eliminated, the US Navy's primary worry was attack from land based aircraft, with kamikazes becoming the greatest threat. By the end of the war, a new auto-loading 3 inch AA gun was in development which could fire 50 rounds per minute. Tests showed that it was as effective against kamikazes as five 40mm gun quads mounts with a total of 20 barrels. (267-8) By the February 1945 naval air raids on Japan, 70 % of carrier aircraft were fighters, and they protected the fleet by arriving early over Japanese air bases and dominating the skies. (Morison, Victory 21) Had the Japanese carrier force survived into 1945, it would have faced a vastly improved American fighter plane, the Bearcat, which was being delivered as the war was ending, and new attack aircraft like the Skyraider which could carry as much as 8,000 pounds of bombs. (Dunnigan and Nofi 210, 219) The Bat, the world's first radar equipped self guided glide bomb, a revolution in naval technology, was first used in 1945. (Rowland 342-3) But with the US fleet largely invulnerable to Japanese air power by 1944, poor Japanese anti-aircraft protection, and overwhelming US numbers, the Japanese fleet didn't stand a chance of surviving through 1944. With the destruction of Japanese naval aviation went any hope that Japan had of victory.
Cressman, Robert J., "Carrier Strike Through Mountain Passage." World War II Magazine. November 1986
Dunnigan, James F. and Albert Nofi., Victory at Sea: World War II in the Pacific. Quill., 1996
Hughes, Wayne P., Fleet Tactics. Annapolis: Naval Institute Press, 1986.
Lundstrum, John B., The First Team. Annapolis:Naval Institute Press, 1984.
Macintyre, Donald., Wings of Neptune. New York: W.W. Norton and Co., 1963.
Morison, Samuel Eliot., History of US Naval Operations in WWII. Breaking the Bismarcks Barrier, Victory in Pacific
Reynolds, Clark G., The Carrier War. Alexandria, Va: Time-Life Books, 1982.
Rowland, Buford, US Navy Bureau of Ordnance in World War II. Government Printing Office.
Wukovits, John F., "Scratch One Flattop:, World War II Magazine., September 1988.
Ship models are from the US Naval Academy in Annapolis and US Navy Museum in Washington.
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