Air warfare, Southwest Pacific Area
Separate from close air support in amphibious warfare, air warfare in the Southwest Pacific Area theater of World War II under Douglas MacArthur, were a considerable part of warfare in that region. There is no corresponding article for the Pacific theater under Chester W. Nimitz, because his air operations were tied to amphibious operations and combined sea battles; the strategic bombing of Japan remained under control of Washington.
MacArthur, however, did have significant land-based air, and an extremely competent air component commander General George Kenney. Kenney never had enough planes, pilots or supplies. He was not allowed any authority whatever over the Navy's carriers; coordination depended on personalities and politics. Admiral William Halsey, in his autobiography, was critical of Kenney in the Leyte campaign. 
But the Japanese, after their initial victories, were always in worse shape--their equipment deteriorated rapidly because of poor airfields and incompetent maintenance. The Japanese Navy had excellent planes and pilots in 1942, but they lost planes, pilots, and aircraft carriers faster than they could be replaced. There was even worse cooperation between the Japanese Navy and Army than between MacArthur and Nimitz, or the United States Navy and United States Army in general. Japanese Army, and land-based air commanders, generally planned poorly and squandered their resources. Once U.S. production was mobilized and an effective aircrew recruiting and training process in place, there was no quantitative way in which Japan could have more than a local air advantage.
Theoretically, Japanese doctrine stressed the need to gain air superiority, but the infantry commanders repeatedly wasted air assets defending minor positions. When Arnold, echoing the official Army line, stated the Pacific was a "defensive" theater, Kenney retorted that the Japanese pilot was always on the offensive. "He attacks all the time and persists in acting that way. To defend against him you not only have to attack him but to beat him to the punch."
The war began with a devastating Japanese air strike on the air bases in the Philippines, many hours after the Pearl Harbor attack. Kenney had wanted to launch a long-range attack against Okinawa, but MacArthur overruled him.
There was no effective fighter defense over the main bases, even though there was no strategic surprise as in Hawaii.
Key to Kenney's strategy was independent air operations to neutralize of bypassed strongpoints like Rabaul and Truk through repeated bombings. One obstacle was "the kids coming here from the States were green as grass. They were not getting enough gunnery, acrobatics, formation flying, or night flying." So he set up extensive retraining programs. The arrival of superior fighters, especially the twin-tailed P-38 Lightning, gave the Americans an edge in range and performance.
Carrier-based aircraft occasionally joined in large raids, but the long-range land-based aircraft could conduct a continuous campaign of attrition.
High-flying B-17 heavy bombers almost never could hit moving ships. although they were useful in finding them, as well as in attacking strongpoints on land.
Kenney developed effective methods using B-25 Mitchell medium bombers teaching pilots the effective new tactic of skip bombing: flying in close to the water then pulling up and lobbing bombs that skipped across the water and into the target. He also modified the medium bombers to carry unprecedented numbers of forward-firing machine guns; the concentrated fire of 14 .50 caliber machine guns could tear apart transports and unarmored warships. Occasionally a ripe target appeared, as in the Battle of the Bismark Sea (March, 1943) when bombers sank a major convoy bringing troops and supplies to New Guinea. That success was no fluke.
Supplies were always short in the Southwest Pacific--one enterprising supply sergeant on Guadalcanal ordered engine gaskets from Sears, and thanks to the highly efficient mail service received them quicker than through regular channels. Kenney finally rationalized the supply system, but had no good solution to the lack of reinforcements. Airmen flew far more often in the Southwest Pacific than in Europe, and although rest time in Australia was scheduled, there was no fixed number of missions that would produce transfer back to the states. Coupled with the monotonous, hot, sickly environment, the result was bad morale that jaded veterans quickly passed along to newcomers. After a few months, epidemics of combat fatigue would drastically reduce the efficiency of units. The men who had been at jungle airfields longest, the flight surgeons reported, were in bad shape:
Many have chronic dysentery or other disease, and almost all show chronic fatigue states. . . .They appear listless, unkempt, careless, and apathetic with almost masklike facial expression. Speech is slow, thought content is poor, they complain of chronic headaches, insomnia, memory defect, feel forgotten, worry about themselves, are afraid of new assignments, have no sense of responsibility, and are hopeless about the future. 
The Army and Marines had different styles of close air support.
Army close air support
At Guadalcanal, the Bell P-400 Aircobras lacked turbochargers to dogfight at altitude, but were effective at close air support, to the delight of the mud soldiers. When Stalin asked for 500 additional Lend-Lease planes in 1942, he specified he did not want any more of the Curtiss P-40 Tomahawks, because it "was not up to the mark in the fight against modern German fighter planes." In a frantic technological race against the Nazis, American designers created a series of fighters and bombers that had the speed, climb-rate, maneuverability, and range to do the job.
Marine close air support
The Marines had their own land-based aviation, built around the excellent Chance Vought F4U Corsair, an unusually big fighter-bomber. By 1944, 10,000 Marine pilots operated 126 combat squadrons. Marine Aviation originally had the mission of close air support for ground troops, but it dropped that role in the 1920s and 1930s and became a junior component of naval aviation. During that period, the mission was to protect the fleet from enemy air attacks, but it soon swung back to direct support of ground operations.
Marines were too lightly armed to employ the sort of heavy artillery barrages and massed tank movements the Army used to clear the battlefield. They relied on aggressiveness and speed; Marines might well make frontal attacks while Army troops waited for artillery preparation.
The Japanese were so well dug in that Marines often needed air strikes on positions 300 to 1,500 yards ahead. Naval gunfire could help at times, but the flat trajectories of naval guns were not optimal for plunging into land fortifications. The Marines pioneered control of fire support, both air and naval gunfire, through various doctrinal revisions, but eventually with a function that continues today, the Air Naval Gunfire Liaison Company (ANGLICO).
This reflected the long-held Marine commitment that every member of the Corps, from commandant to pilot to company clerk, absolutely had to be proficient as a rifleman and understand ground conditions. There was an enormous difference in the understanding of a Marine pilot qualified to lead the infantry he was supporting, and Navy and Air Corps pilots with little understanding of close-range ground combat. The Marine formula increased responsiveness, reduced "friendly" casualties, and (flying weather permitting) substituted well for the missing armor and artillery.
- William F. Halsey and J. Bryan III (1947), Admiral Halsey's Story, McGraw-Hill, p. 230, p. 241
- Kenney, Kenney Reports 112; Leary, We Shall Return p 99; Quesada 39
- A. Mae Mills Link and Hubert A. Coleman, Medical Support (1955) 851;