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Close Air Support: The Pioneering Years

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Naval History, December 2012
Marine aviators’ commitment to deliver support to ground forces—a tactic once deemed too dangerous—grew into a hallowed hallmark of the Corps.

Modern Marine Corps aviation is a powerful combat arm, organized and equipped to perform its primary functions of assault support, antiaircraft warfare, offensive air support, electronic warfare, control of aircraft and missiles, and reconnaissance. The integration of those roles enables the air-combat component to fully support the ground-combat campaign. Mastery of those functions also allows Marine aviation to achieve its most distinctive competence—the ability to deliver close air support (CAS) to Marines on the ground.

Close air support is defined as “air action by fixed- and rotary-wing aircraft against hostile targets that are in close proximity to friendly forces and require detailed integration of each air mission with the fire and movement of those forces.” Inherently dangerous to airmen and infantry alike, this extreme form of fire support requires extraordinary coordination to deliver safely. Marine riflemen take a personal interest in the proximity of close air. “Close” to them means damned close, and they know it when they see it.

The Marine Corps celebrated the 100th anniversary of the birth of Marine aviation on 22 May 2012, honoring the date in 1912 when First Lieutenant Alfred A. Cunningham reported for flight training in Annapolis, Maryland. Cunningham became not only the first Marine to qualify as a naval aviator, but also a visionary crusader for a unique, expeditionary air force. Cunningham took keen interest in the first military use of aircraft by Italian aviators against Turkish troops in 1911. He urged Major General Commandant William Biddle to establish a Marine flying program. Under congressional pressure to expedite the Marines’ transition to their advanced naval base–defense mission, Biddle viewed Cunningham’s proposal as an opportunity to demonstrate progress. He recommended the creation of a Marine aviation capability to enhance the combat effectiveness of the advanced-base force. The Navy Department accepted this as a commitment to modernization, and the Corps never looked back.

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On 20 August 1912, Cunningham successfully completed his solo flight, becoming the fifth naval aviator and the first Marine to earn his wings. Other Marine infantry officers—Bernard Smith, William McIlvain, Francis “Cocky” Evans, and Roy Geiger—soon followed. Yet among the Corps’ pioneer fliers, it was Cunningham who possessed the vision and perspective to become the unofficial “father” of Marine aviation. He never lost sight of the Marines’ basic role as an expeditionary force-in-readiness. As early as 1917 he envisioned the primary, redeeming purpose of Marine aviation to be the direct tactical support of the Corps’ infantry operations. Technically premature at the time, the seed he planted would bear fruit ten years later in Nicaragua, when a squadron of Marine biplanes employed low-level bombing attacks to rescue a besieged infantry force. Marines have fought their country’s battles as an air-ground, combined-arms team ever since.

Fifty pilots, gunners, and mechanics made up the aviation detachment of the Marine advanced-base force in April 1917 when President Woodrow Wilson asked Congress to declare war against imperial Germany. The new commandant, Major General George Barnett, sought a combat role for Marine ground and aviation components. In June the secretary of War accepted Barnett’s offer to include the veteran 5th Marine Regiment with the first increment of U.S. Army troops to deploy to France. When the 6th Marines and a machine-gun battalion later followed, the three Leatherneck units coalesced into the 4th Brigade of Marines—at 10,000 strong the largest force ever fielded by the Corps to that time. The War Department, however, rejected Barnett’s subsequent offer—Cunningham’s proposal for land-based Marine air squadrons to provide reconnaissance and artillery spotting for the brigade.

But the Navy agreed to accept the Marines’ advanced-base seaplane squadron for antisubmarine patrols in the Azores. And in August 1918 Captain Cunningham led four land-based bomber squadrons, the 1st Marine Aviation Force, to northern France in support of an Allied naval bombing group. The war-weary British and Belgian forces welcomed the arrival of these 900 cocky volunteers, who flew two-seater DH-4 and DH-9A biplanes to bomb German installations behind the lines.

When their service as sub-hunters and bombers ended in 1918, the surviving Marine aviators returned to airfields at Parris Island, South Carolina; and Quantico, Virginia, in early 1919, proud of their contributions to the Allied victory. They had demonstrated a commendable readiness for expeditionary service by being able to deploy rapidly, operate economically, and engage the enemy in close combat. Those attributes helped the fledgling Marine air arm survive the massive postwar downsizing that followed.

Alfred Cunningham sought to validate the distinctive rationale for a separate Marine air component before the General Board of the Navy. “The only excuse for aviation in any service,” he testified in April 1919, “is its usefulness in assisting the troops on the ground.” Cunningham envisioned a combat-air arm capable of direct battlefield support of infantry operations that would enable Marines to fight stronger foes, farther afield—expeditionary air squadrons that could deploy by ship and fly from primitive fields in support of ground units or advanced-base forces.

The Marines had to develop competency in close air support on the move. Barely had the troops returned from Europe when the Western Hemisphere fire-bell started clanging. Marines were quickly deployed to Hispaniola and Nicaragua to quell disorders and protect American interests. Marine regiments and aviation squadrons fought insurgents for the next 14 years in the so-called Banana Wars. As arduous as those expeditions became, the Marines were the nation’s only armed force in combat during the interwar years. Lessons learned in close air support tactics and coordination proved invaluable.

British, German, and U.S. Army aviators had experimented with dive-bombing tactics during World War I, but the risk of ground fire prompted most pilots to bomb horizontally from high altitude. In Haiti in 1919, Lieutenant Lawson Sanderson launched the first “diving attack” under fire in Corps history. Flying a Great War–surplus DH-4 without bomb racks, Sanderson aimed the nose of his plane at a 45-degree angle toward a cluster of armed insurgents, and at an altitude of 250 feet released his bomb from an improvised flour sack, “like shaking a cat out of a bag.” 5

In the meantime, the Army Air Service continued to develop and teach dive-bombing tactics at the Advanced Flying School at Kelly Field, Texas. In 1923 Captain Ross “Rusty” Rowell, a 17-year infantry veteran turned aviator, became the first Marine officer to graduate. Rowell, who would replace Cunningham as the chief CAS proponent of the Corps, took command of an observation squadron and taught his pilots what he had learned of low-level attacks from the Army.

In 1926 President Calvin Coolidge requested more Marines ashore in Nicaragua to reinforce the government there against a well-armed revolutionary movement led by Augusto Sandino. Major General Commandant John Lejeune ordered an infantry battalion and Rowell’s observation squadron to the embattled country. Rowell got there first. The squadron established a flying field outside Managua, reassembled their crated aircraft, and commenced operations in support of the 2d Marine Brigade.

In July 1927, Sandino rejected an amnesty and withdrew to the mountains along the Honduran border. An infantry column of 90 Marines and Nicaraguan constables tracked the Sandinistas as far as the village of Ocotal, lost the trail, and established a bivouac in a building. Sandino counterattacked that night with several hundred mounted gunmen, surrounded the house, and riddled the walls with bullets. At mid-morning on 17 July, a pair of Rowell’s DeHavillands appeared overhead and discovered panel markers laid out in the courtyard that signaled: “Attacked by Sandino. One dead, several wounded. Need help.”

The patrol flew back to Managua to report the emergency. Rowell recognized a rare opportunity for close air support—enemy troops in the open, friendly positions clearly identifiable. He ordered five DeHavillands loaded with the optimum mix of bombs and fuel for the 220-mile round-trip mission, and took off. The squadron reached Ocotal late in the afternoon and peeled off into attack formation.

“It was our first experience in real fighting,” Rowell reported, “and in order to get results we [had] to employ low-altitude bombing.” He led the attack, aiming at a building full of Sandinistas firing at the Marine compound, and released his bomb so close to the ground that the next pilot exclaimed, “He almost touched his wheels on the roof!” As the bomb exploded, Rowell banked the plane into a climb, clearing a field of fire for his rear gunner. The other pilots sought to exceed Rowell’s low release. The sudden air attacks surprised and scattered the Sandinistas, who to this point had regarded the biplanes more a nuisance than a threat.

Breaking the siege at Ocotal may have meant little in the long insurgency, but the air attacks represented an indelible turning point for Marine aviation and the Corps. For the first time in combat, Leatherneck aviators had delivered close air support to rescue a besieged ground force. The lesson was not lost on certain veteran infantry officers who had reserved judgment on the unproven air arm. Ocotal was followed a few months later by Quilali, where Lieutenant Christian Schilt landed his stripped-down fighter in the cliff-side village ten times under fire to rescue 18 badly wounded Marines, convincing the last skeptics to accept Marine aviators as combat equals. The two events provided a rock-solid foundation for the Marine air-ground, combined-arms team. 8

The Marine brigades returned from Nicaragua and Haiti in 1933 just as the Corps began changing its primary mission from the static defense of advanced bases to one more suitable for a likely war with Japan—offensive amphibious warfare, the forcible seizure of strategic islands in a naval campaign across the Pacific. Encouraged by the tactical performance of Marine aviation in Nicaragua, the Corps leadership incorporated the air-ground team concept in a series of landmark doctrinal initiatives. The new Fleet Marine Force brigades, formed in 1933 at Quantico and San Diego, contained an air group and an infantry regiment.

Yet there were few opportunities to improve CAS procedures. Reliable air-ground radios were scarce, and the Marines had yet to determine whether dive-bombers, fighters, or an entirely new ground-attack aircraft were best suited for the close air mission.

In 1941 the Corps commissioned the 1st and 2d Marine Air Wings, commanded by Brigadier Generals Roy Geiger and Ross Rowell, respectively. By 7 December the Marine Corps had deployed six of its 13 air squadrons to the Pacific, mainly at Ewa Field, Hawaii. Three days earlier the carrier Enterprise had reinforced the Wake Island garrison with the advance echelon of Marine Fighting Squadron (VMF) 211 with 12 brand new Grumman F4F Wildcats.

Surprised at Pearl Harbor and overwhelmed at Wake Island, the Marines lost many aircraft in the first weeks of war. Desperate months of fighting—outnumbered and outgunned—extended through the Battle of Midway in early June 1942. Two months after that, the Allies launched the first offensive campaign in the Pacific, the amphibious seizure of Guadalcanal.

The 1st Marine Division landed on 7 August 1942, captured the nearly completed Japanese bomber strip, and dug in to withstand relentless Japanese counterattacks. Major General Alexander A. Vandegrift put his engineers to work on the airfield and on 12 August called for Marine air: “Airfield Guadalcanal ready for fighters and dive bombers.”

On 20 August the USS Long Island (CVE-1) turned into the wind 200 miles east of Guadalcanal and launched Captain John Smith’s VMF-223 and Major Richard Mangrum’s Marine Scout Bombing Squadron (VMSB) 232. The Grumman F4F Wildcats and the Douglas Dauntless SBD-3s landed that evening on the airfield to cheers from the riflemen manning the perimeter. More Marine squadrons ran the gauntlet of Japanese patrols to reach Guadalcanal from staging bases in New Caledonia and Efate in the New Hebrides. On 3 September 57-year-old Major General Roy Geiger, the fifth Marine aviator, arrived to take command of the 1st Marine Air Wing.

With the arrival of the first Vought F4U Corsair squadrons, the Marines gained the upper hand definitively in the battles for air supremacy over the Solomons. More powerful and much faster than the Wildcat it replaced and the Nakajima Zero it often dueled, the Corsair would soon endear itself to a generation of Marine riflemen in the western Pacific, and later in Korea, for its prowess as a ground-attack instrument.

But the five-month battle for Guadalcanal offered few opportunities for aviation missions in direct support of the ground fighting. As long as the battle hung in the balance, Marine fighters and dive-bombers were urgently needed to interdict Japanese air raids and reinforcement convoys steaming down “the Slot” from Rabaul.

After Guadalcanal, the Marines rarely fought again as an air-ground team throughout the next 20 months. In November 1943 the Joint Chiefs of Staff opened a new front in the Central Pacific, which would commit most Marine ground forces to a series of island-hopping campaigns through the war’s end. The vast distances between the island objectives and the scarcity of nearby airfields made it difficult for land-based Marine aviation to close the range. Aircraft carriers seemed the obvious answer, but the Navy was disinclined to replace its own air groups with Marines. The problem remained unresolved until August 1944, when Pacific Fleet commander Admiral Chester Nimitz agreed to accept Marine air-support squadrons on escort carriers in future amphibious campaigns. Implementing the decision took time. Marine ground forces would not fully enjoy the benefit of carrier-based Marine air cover until Okinawa.

The need for closely coordinated CAS in amphibious assaults became evident at Tarawa, the first objective in the Central Pacific drive. Navy squadrons flying from escort carriers were assigned for the Marine assault, but the air group and the Marines had no opportunity to train together, not even during the rehearsal landings. On D-day, amid the chaos of the first opposed amphibious assault of the war, the Marines ashore could not communicate directly with the air support to designate targets or cease errant friendly fire. Those problems took time to improve.

General Geiger, the first Marine aviator to command a joint-service amphibious corps, waged successful campaigns at Bougainville, Guam, Peleliu, and Okinawa. Appreciating the synergy of the Marine air-ground team, he sought ways to bridge the gap with the land-based squadrons cooling their heels in the South Pacific. That finally worked at Peleliu, close enough to Allied airstrips in New Guinea for the 2d Marine Air Wing to stage through to the Palaus.

The advance elements began landing on Peleliu’s newly captured airstrip one week after D-day. On 26 September 1944, Major Robert Stout’s VMA-114 launched from Peleliu and executed the war’s first significant Marine close air mission in direct support of a Marine landing, a battalion-sized assault on nearby Ngesebus Island. Stout’s 20 Corsairs strafed the beach defenses in screeching runs just 30 feet off the water, barely ahead of the landing craft, blazing a path for the Marines to overwhelm a larger force and capture the island.

The fighter pilots next flew missions in support of the decimated battalions attacking Japanese caves at Peleliu’s Bloody Nose Ridge. The Corsair squadrons introduced two new close-air weapons—napalm tanks and rockets. Napalm worked best. The pilots flew the shortest “wheels-down” missions in Corps history, dropping the napalm on designated targets and landing to reload within three minutes. This was Ocotal writ large: Marine pilots dropping ordnance at extremely low altitudes, doing their damnedest to help Marine riflemen in dire straits.

The experience of using an area weapon such as napalm in close air support underscored the need for closer air-ground coordination. The Marines adopted the practice of assigning air liaison parties (ALPs)—typically a “dismounted” aviator and a radio operator—to accompany infantry commanders, much as artillery forward observers. The terse, often profane dialogue between the pilot on the ground and his former squadron-mates overhead paid many dividends. Landing-force aviation control units began coordinating ALPs in the bigger battles of Iwo Jima and Okinawa.

Marine aviation opened the show at Iwo Jima in spectacular fashion when two squadrons of Corsairs swept in extremely low to strafe defenses along the seven landing beaches on D-day. It was a memorable yet ephemeral display of Marine air-ground teamwork. Few veterans among the 4th and 5th Marine Divisions streaming ashore had seen Marine air in combat, nor would they see it again during the five-week battle. The Corsairs came from the eight Marine squadrons serving on board fleet carriers of Task Force 58, on its way to strike Japan. Navy and Army Air Forces pilots flew the ensuing CAS missions for the infantry, coordinated by Marine Colonel Vernon McGee’s Landing Force Air Suppot Control Unit.

Marine aviation reached its peak strength in 1944 with 112,000 personnel (10,000 pilots), five air wings, and 126 aircraft squadrons. For many squadrons, however, the desperate fighting in the Solomons had been replaced by humdrum air raids on bypassed Japanese bastions. Impatient air units in the backwaters rejoiced when General Douglas MacArthur, commanding the Southwest Pacific theater, asked for Marine aviation support in his reconquest of the Philippines.

In December 1944, elements of the 1st Marine Air Wing began staging into muddy airfields in Leyte in support of MacArthur’s huge invasion force. Here at last was full-scale warfare on a series of very large islands—not coral atolls—and the Marines pitched in with relish, intercepting Japanese air raids, attacking shipping, covering major amphibious landings at Ormoc and Lingayen, delivering low-level close air support to facilitate the 1st Cavalry Division’s drive on Manila. Marine aviation liaison officer Lieutenant Colonel Keith McCutcheon emerged as the key mentor and facilitator for CAS missions for Army infantry units, the finest sustained support of the Pacific war.

Okinawa was the largest air-ground-sea battle of the Pacific war. Generals Roy Geiger and Francis Mulcahy, veterans of the 1st Marine Aviation Force in World War I, commanded III Amphibious Corps and the field army’s Tactical Air Force, respectively. More than 700 Marine aircraft supported the fighting, many flying close air missions for the first time from escort carriers.

Combat assignments ranged from intercepting massive Japanese kamikaze suicide planes to airdropping rations, medicine, and ammo to infantry units marooned by incessant rain and mud. Marine ALPs kept pace with each battalion commander to request more than 5,000 CAS sorties and direct (but not control —the front was too narrow) aircraft to the target. In many cases the pilots delivered ordnance on targets within 200 yards of frontline troops.

Fittingly, Lieutenant General Geiger was the senior Marine Corps representative on board the USS Missouri (BB-63) in Tokyo Bay for the Japanese surrender ceremony. His final contribution to the Corps came a year later, after observing the test of an atomic bomb that sank an anchored fleet of obsolete ships in Bikini Atoll in the Marshalls. In an urgent report to the commandant, Geiger warned, “a small number of atomic bombs could destroy an expeditionary force such as now organized, embarked, and landed.” He said he could not visualize another landing such as Normandy or Okinawa against an enemy in possession of such bombs. 9

General Vandegrift, now commandant, convened a special board under General Lemuel Shepherd to recommend major modifications to amphibious doctrine in the Atomic Age. The Shepherd Board’s report was a landmark for both the Corps and Marine aviation. It recommended the service establish an experimental helicopter squadron at Quantico (the future HMX-1) and acquire carrier-based Marine helicopters for the vulnerable ship-to-shore movement. HMX-1 received its first prototype helicopters and published a draft manual, Employment of Helicopters , in 1948.

In August 1950, five weeks after the North Korean invasion of the Republic of Korea, the 1st Provisional Marine Brigade arrived in Pusan, the last port remaining to the U.N. allies. The brigade deployed as an integrated air-ground team—the veteran 5th Marine Regiment paired with Marine Air Group 33 (two Corsair squadrons, a night-fighter squadron, and a light observation squadron equipped with four HO3S Sikorsky helicopters). The embattled U.S. 8th Army quickly used the team as a “fire brigade” to counterattack North Korean penetrations of the Pusan Perimeter.

In every engagement, the brigade’s two fighter squadrons flew CAS missions from escort carriers on station in the western Sea of Japan. The combined firepower proved decisive in a series of clashes with tank-led North Korean forces along the Naktong River. The small-scale tactical victories bought time and raised morale. In September the balance of the 1st Marine Division arrived, embarked and reabsorbed the brigade, and sailed into the Yellow Sea for General McArthur’s surprise amphibious landing at Inchon. The brigade had fought well as a team, serving notice to the U.N. allies and North Koreans that the Marines had come to this new war packing a lethal punch.

The 1st Marine Division and the 1st Marine Air Wing were reunited in common cause for the first time since Guadalcanal. Never was Marine close air support more desperately needed, nor so responsively provided, than during the 90-day period between the Inchon landing in September and the fighting breakout of the division from the Chosin Reservoir in December. Marine pilots launched their F4U-5 Corsairs from escort carriers or expeditionary airfields ashore to deliver precise close air support to battalions landing under fire at Wolmi-do Island, Inchon’s seawalls, and the fortified north bank of the Han River. They banked sharply around Seoul’s high-rise buildings to strafe and bomb North Korean barricades ahead of Marine tank-infantry attacks. And, with the Marines fighting to extricate themselves from ten Chinese divisions during the coldest winter in memory around the Chosin Reservoir, the air wing kept its Corsairs constantly overhead in a one-mile swath, on call, every daylight hour, from Toktong Pass back to the port of Hungnam and the guns of the 7th Fleet.

At the end, Major General Oliver P. Smith, commanding the division, spoke from the heart as he commended the 1st Marine Air Wing: “Never in its history has Marine aviation given more proof of its indispensible value to ground Marines. A bond of understanding has been established that will never be broken.” 10

The Marines’ major innovation in this vicious, undeclared “police action” was the operational use of helicopters to deliver assault troops to seize distant objectives, a new capability equally valuable in seaborne landings and mountain warfare. Marine Helicopter Squadron 161 arrived in Korea in September 1951, equipped with new Sikorsky HRS-1 transport helicopters, and shortly made military history by executing the first tactical lift of infantry troops in combat. Conceived, developed, and deployed within five years of the Shepherd Board’s visionary report, the Marine transport choppers quickly became a principal component of the air-ground team.

The doctrine of Marine close air support, refined and revalidated in combat during the first 25 years after its trial by fire in Nicaragua, still provides the adhesive that bonds the air-ground team. Modern practitioners of the art are mindful of the risks and visions of the first pioneers. As a boy in the 1890s, Roy Geiger had tried to fly by wiring turkey wings to his arms and flapping vainly off a roof. Alfred Cunningham’s 1915 attempt to be the first Marine aviator to launch by catapult from an underway warship nearly killed him. Both survived and flourished, flying by the seats of their pants, always thinking ahead. Later pioneers—Rusty Rowell, Keith McCutcheon, and Vernon McGee—made the concept of Marine close air support a reality.


1. U.S. Marine Corps, Concepts and Programs, 2011, 15.

2. Joint Publication 1-02, DOD Dictionary of Military and Associated Terms , 8 November 2010, as amended through 15 March 2012.

3. The earliest aviators learned to fly in “pusher aeroplanes,” seated in front of the rear-facing, four-cycle engine, which propelled the craft from behind.

4. Cunningham’s testimony before the General Board of the Navy on 7 April 1919 is repeated in his essay “Value of Aviation to the Marine Corps,” Marine Corps Gazette , September 1920, 222.

5. LTGEN Lawton Sanderson, oral history interview, 14 July 1969, Marine Corps Oral History Collection, History Division, Marine Corps University. Interview with Sanderson, “Straight on Target,” Leatherneck , July 1944, 23.

6. MAJ Ross Rowell, “The Air Service in Minor Warfare,” U.S. Naval Institute Proceedings , October 1929, 873. Rowell, after-action report, “Battle of Ocotal,” 16 July 1927, Rowell biographic files, Reference Section, History Division, Marine Corps University.

7. COL Thomas C. Turner, “Flying with the Marines in Nicaragua,” Leatherneck , March 1931, 7.

8. Rowell and the other four aviators at Ocotal were the first Marines to receive the Distinguished Flying Cross. President Coolidge presented Christian Schilt the Medal of Honor for “almost superhuman skill combined with personal courage of the highest order” at Quilali.

9. LTGEN Roy Geiger to CMC, “Report on Able and Baker Atomic Bomb Tests held at Bikini Atoll, July 1946,” 21 August 1946, 2, Reference Section, History Division, Marine Corps University.

10. MAJGEN O. P. Smith to MAJGEN Field Harris, 20 December 1950, Reference Section, History Division, Marine Corps University.