The Pacific War was the heyday of the aircraft carrier. Before war broke out, carriers were regarded as an important supporting element for the battle line; by the time the war ended, they effectively were the battle line, displacing battleships as the queens of the fleet. Five major carrier engagements were fought during the war: Coral Sea, Midway, Eastern Solomons, Santa Cruz, and Philippine Sea. By contrast, there were only two battleship engagements: Guadalcanal and Surigao Strait.
Aircraft carriers themselves are nothing but floating airfields. A few of the earliest carriers, converted from battle cruiser hulls under the terms of the naval disarmament treaties, carried 8" (20cm) guns and had substantial armor belts. But most carriers were armed only with dual-purpose and antiaircraft guns, and their armor protection was comparable to that of a cruiser. Their power lay in their air groups, which typically were composed of three to five squadrons of fighters and light bombers, a total of 60 to 90 aircraft. Whereas a battleship could fire shells to a distance of perhaps 30 miles (and rarely hit a maneuvering target at that distance), the air group of an aircraft carrier could project accurate firepower out as far as 300 miles. Its aircraft also gave a carrier group a tremendous search area.
An aircraft carrier had to have a combination of high speed and a long flight deck to operate a large air group. Carrier commanders thought in terms of the deck load strike, which was the largest group of aircraft that could be assembled on deck and successfully launched in a single operation. Aircraft were spotted (positioned on deck for launch) by the flight deck crew, who manhandled the aircraft into place. In 1943, the Americans began equipping their aircraft carriers with jeeps equipped to hitch to the aircraft and move them more rapidly. Fighters were invariably stationed in front to be launched first, in spite of their lesser endurance, because they required a shorter deck run to get airborne. American carriers were equipped with catapults to decrease the minimum required run, which allowed them to operate larger groups of heavier aircraft. Japanese carriers also began to be equipped with catapults just before war broke out, starting with the Shokakus.
It was also necessary to get the aircraft back down
after they completed their mission. Arrestor wires were used to bring
landing aircraft to a quick halt. These were steel cables suspended
across the rear half of the flight deck, just above deck level, where
they could be caught by a tail hook lowered from the rear fuselage of a
carrier aircraft. The arrestor wires were hydraulically loaded so that
they offered considerable resistance to being pulled forward by the
aircraft, thereby bringing the aircraft to a rapid halt.
There was also a crash barrier forward of the arrestor wires. This was a strong net about 15 feet high. If the tail hook failed to catch any of the arrestor wires, or if an arrestor wire malfunctioned, the crash barrier prevented the aircraft from rolling into the forward area of the flight deck, where aircraft that had just landed or were about to take off were usually parked. The crash barrier was a last ditch: An aircraft that went into the crash barrier was likely to be damaged, and its crew could easily be injured.
Once an aircraft landed, the crash barrier was lowered and the aircraft taxied forward to make room for the next aircraft to land. Aircraft could then be moved the hangar deck for maintenance, using large deck elevators. Early carriers placed these elevators down the centerline of the flight deck, but beginning with the Wasp, carriers began to be built with elevators on the edges of the flight deck, where they would be less likely to interfere with flight operations if they malfunctioned.
Most Japanese and American carriers could carry more aircraft than they could effectively operate, and the number of aircraft that could be operated also depended on the size of the aircraft. This leads to some ambiguity in the aircraft carrying capacities quoted for aircraft carriers. Unless otherwise noted, the aircraft capacities listed in this encyclopedia are the nominal operating capacities at the time the ship went into war service.
Both Japanese and American carriers proved potent but fragile. Their air groups could wreak tremendous damage on the enemy, but the carriers themselves were a highly vulnerable combination of gasoline tanker and munitions ship, albeit with heavy antiaircraft defenses and some armor protection. The Americans greatly improved their damage control techniques during the war, which allowed some carriers (such as the Franklin) to make it home in spite of incredible damage. The Japanese did not improve their damage control as much and continued to lose carriers unnecessarily.
A peculiarity of Japanese carriers was
that, whereas Allied
carriers used landing signal officers (LSOs) equipped with signaling
paddles to
guide aircraft in to land, the Japanese carriers used an ingenious
system of
signal lamps. On each side of the flight deck, a red lamp was
mounted thirty to fifty feet aft of a green lamp. A Japanese
carrier pilot only needed to aim between the pairs of lights and adjust
his
glide path so that the red lamps appeared to be just above the green
lamps. The system was effective enough that even the poorly
trained carrier pilots of 1944
were usually able to get their planes
down safely. Its only limitation was that there was no way to
signal speed adjustments. The U.S. Navy developed similar
systems only after the war ended.
Another difference between Japanese and American
carrier design was that the Japanese insisted on refueling and rearming
aircraft on the hangar decks. The Americans preferred to refuel and
rearm on the flight deck. Japanese carriers typically had two
hangar decks enclosed by the hull, while American carriers typically
had a single open hangar deck. As a result, the Japanese had a longer
turnaround time for rearming and refueling their aircraft, and any bomb that penetrated a Japanese flight
deck exploded in an enclosed and poorly-ventilated space, with the kind
of consequences seen at Midway.
British
carrier operations were
restricted to the Indian
Ocean until late 1944,
and there was never a carrier battle between the British and the
Japanese. This was just as well for the British.
Their aircraft
carriers had armored flight decks and other features that made them
considerably less vulnerable to damage than American or Japanese
carriers. This
became clear during the Okinawa
campaign, when kamikazes
hit several British carrier flight decks without putting the ships out
of
action. But the armored decks came at the cost of smaller air
groups, and
the British carrier punch was further weakened by the miserable quality
of
British naval aircraft. It was only after the British began
using
American naval aircraft provided under Lend-Lease
that their carriers could operate effectively against the Japanese.
Even then, one series of strikes by the British resulted in the loss of
41 aircraft out of 378 sorties.
There are striking similarities between the development
of aircraft carriers by Japan and the United States. Both experimented
with a single small converted carrier immediately after the First World
War, Hosho in the case of the
Japanese and Langley for the Americans. Both
then converted two capital ship hulls to large carriers in accordance
with the naval
disarmament treaties, Akagi and Kaga
for the Japanese and the Lexingtons for the Americans.
Both then experimented unsuccessfully with a "minimum carrier" design, Ryujo
for the Japanese and Ranger
for the Americans. Both then settled on a larger carrier design, Soryu
and its near sister Hiryu for the Japanese and the
first two Yorktowns for the Americans. At
this point, with the collapse of the treaty structure, the two powers
diverged. The Japanese rapidly completed the excellent Shokakus,
while the Americans rushed to completion a third Yorktown and another "minimum carrier", Wasp,
originally designed to use the remaining displacement allowed under the
now-lapsed treaties.
The Japanese and Allied aircraft carrier
fleets were fairly
balanced at the start of the war. The Japanese had ten
aircraft carriers,
but only six were first-line
carriers capable of operating large air
groups. The Americans had seven aircraft carriers, one of
which (the Ranger)
never served in the Pacific because of its design flaws. The
other six
were comparable to their Japanese counterparts, but they were committed
piecemeal to the Pacific theater because of the priority given to the
European
war. The British did not have a single carrier in the Far East when war
broke out, but had deployed four carriers to Ceylon by 1943 that were
roughly equivalent in fighting power to the four Japanese light carriers.
Both sides launched additional carriers during the war, but the United States had a tremendous advantage in new naval construction. The Japanese completed six fleet carriers, four light carriers, and approximately seven escort carriers during the war. The United States completed seventeen fleet carriers of the Essex class, eleven light carriers of the Independence class, and 77 escort carriers, while the British were able to complete a total of thirteen fleet carriers and 41 escort carriers during the time span of the Pacific War. The Japanese would have been overwhelmed even if they had been able to maintain a unit-for-unit quality advantage.
Though Coral Sea and Santa Cruz were clearly Japanese tactical victories, it can be argued that every one of the carrier battles of the Pacific War was a strategic American victory, since the Japanese failed to attain their objectives while the Americans succeeded, at least marginally. At Coral Sea, the Japanese were forced to call off their Port Moresby invasion, while the Japanese victory at Santa Cruz failed to relieve the Japanese land forces on Guadalcanal. The American victories at Midway and Philippines Sea were decisive both tactically and strategically. Only at Philippines Sea did the Americans have a decisive numerical advantage.
The American ascendancy in carrier combat can be traced to three factors.
Recruitment and training. American naval pilots were elite airmen, though not as good as their Japanese opponents at the start of the war. American naval fighter pilot training emphasized deflection shooting and team tactics, which received less emphasis in the Japanese naval fighter arm. This did much to compensate for greater Japanese combat experience and better Japanese aircraft performance (best exemplified by the Zero) early in the war.
With a population 60% greater than Japan's, and with an automobile culture that encouraged the development of mechanical skills, the Americans had a large pool of potential airmen to draw on. They also adopted rotation policies that supported a training organization capable of turning out large numbers of qualified pilots. The Japanese training system would have been inadequate to keep up with the heavy attrition in the South Pacific campaign even if there had been adequate numbers of young Japanese men with the mechanical aptitude required for air combat. The decrease in Japanese pilot skill became apparent as early as 1943.
Fighter direction. Though American fighter direction was inept in the Battle of the Eastern Solomons, it improved considerably thereafter. The Americans were superior in radar technology, which greatly assisted American fighter direction. In addition, American aircraft radios were much superior to Japanese radios, which were so poor that they were often removed by fighter pilots to save weight. The Americans carefully selected and trained fighter direction officers to work from the flag carrier of a task force and coordinate fighter interceptions. Curiously, many were former stockbrokers, who seemed to have an aptitude for correlating data and making snap decisions.
Technology. The American carrier air groups started the war equipped with fighters that were distinctly inferior to their Japanese counterparts. However, by 1944, the Japanese had lost their aircraft performance advantage with the introduction of second-generation Allied aircraft like the Hellcat. Together with the decreasing quality of Japanese pilots, this spelled disaster for the Japanese.
In addition to superior aircraft, the Americans developed superior antiaircraft defenses. American antiaircraft gun directors started out good and steadily got better. The 5"/38 dual-purpose gun was a solid design that was further enhanced with the introduction of the VT radar proximity fuse and radar direction. Air attack on an American carrier task group became an increasingly suicidal activity even for those aircraft that managed to break through the fighter defenses.
Because carriers were a relatively new and untried weapons system, there was much uncertainty on both sides on how they should best be employed. Both sides initially viewed carriers as support units for the battle line, and anticipated that carriers would operate near the battleships during a fleet engagement. However, the organization of 1 Air Fleet on 10 April 1941 reflected a willingness by at least some Japanese naval leaders to mass their carriers as a single strike forces. Meanwhile the Americans experimented with carrier task forces composed of a single carrier screened by cruisers and destroyers. The two approaches reflected one of the unanswered questions tacticians wrestled with early in the war, namely, should carriers be massed? It is normally considered good tactics to mass firepower to avoid risking defeat in detail, but the vulnerability of carriers to air attack led American tacticians to be wary of putting all their eggs in one basket. The disaster at Midway suggested that the Americans had the better argument, but the relatively small number of carriers involved (three for the Americans, four for the Japanese) left considerable uncertainty.
By March 1943 the Americans had concluded that the ideal was two carriers per task force, with the task forces concentrating for strikes and separating by at least 25 miles when air attack seemed imminent. The ideal screen was 20 to 24 destroyers and either six heavy cruisers, or two battleships and four antiaircraft cruisers. The destroyers were stationed in a circle at a radius of 1500 to 2500 yards from the center of the task force, with the heavier warships stationed closer to the carriers. In practice, there were simply not enough screening vessels for such extravagant protection, and most task groups consisted of three or four heavy or light carriers protected by fewer heavy warships and much fewer destroyers than the ideal. For example, Task Group 50.1 at Tarawa had two fleet and one light carrier screened by five heavy cruisers, one antiaircraft cruiser, and just eight destroyers.
By this point in the war, Japanese practice was not much different
than American at the task force level. However, the Japanese often kept
their task forces much more widely separated than the Americans. This
was in part a move of desperation: Task forces containing less capable
light carriers were often employed in a manner that suggests they were
viewed as sacrificial decoys. However, a tendency to have widely
separated forces converge on the objective had characterized Japanese
tactical thinking from the very beginning of the war.
It is notable that history has seen only five carrier battles, all during the Pacific War between the Japanese and the Americans. Carrier combat was a unique feature of that war, unlikely to ever be repeated. Each battle lasted only two or three days, during which both sides experienced heavy losses in their carrier air groups, necessitating the withdrawal of at least part of their surviving carrier forces. Yet the possibility that the enemy might commit his carriers always had to be taken into account when planning operations, which accounts for the dominance of these ships in the Pacific War.
References
The Pacific War Online Encyclopedia © 2007-2010 by Kent G. Budge. Index
