Cactus Air Force refers to the ensemble of Allied air power assigned to the island of Guadalcanal from August 1942 until December 1942 during the most heavily contested phases of the Guadalcanal Campaign, particularly those operating from Henderson Field. The term "Cactus" comes from the Allied code name for the island. In 1943, the Cactus Air Force was absorbed into AirSols, a joint command of Allied air units in the Solomon Islands.

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Cactus Air Force
Cactus Air Force aircraft crowd Henderson Field, Guadalcanal in October 1942
Active	20 August 1942 – April 1943
Countries	United States  New Zealand
Allegiance	Allies of World War II
Branch	United States Army Air Forces United States Marine Corps United States Navy Royal New Zealand Air Force
Type	Ensemble air unit
Role	Aerial warfare
Garrison/HQ	Henderson Field, Guadalcanal, Solomon Islands
Engagements	World War II
Commanders
Notable commanders	Roy Geiger Louis E. Woods Francis P. Mulcahy

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On 7 December 1941, the Japanese attacked the U.S. Pacific fleet at Pearl Harbor, Hawaii. The attack crippled much of the U.S. battleship fleet and led to a state of war between the two nations. In launching this war, Japanese leaders sought to neutralize the American fleet, seize possessions rich in natural resources, and obtain strategic military bases to defend their far-flung empire. Japanese forces also attacked and took control of Hong Kong, the Philippines, Thailand, Malaya, Singapore, the Dutch East Indies, Wake Island, New Britain, and Guam.^[1]

Two attempts by the Japanese to extend their defensive perimeter in the south and central Pacific were thwarted in the Battle of the Coral Sea (May 1942) and the Battle of Midway (June 1942). These two strategic victories for the Allies provided an opportunity to take the initiative and launch a counter-offensive against the Japanese somewhere in the Pacific. The Allies chose the Solomon Islands, specifically the southern Solomon Islands of Guadalcanal, Tulagi, and Florida.^[2]

Allied strategists knew the Japanese Navy occupied Tulagi in May 1942 and constructed a seaplane base near there. During early July 1942, the Japanese Navy began constructing a significant airfield near Lunga Point on nearby Guadalcanal island. After completion, these bases would protect Japan's major base at Rabaul, threaten Allied supply and communication lines across the South Pacific to Australia and New Zealand, and establish a staging base for potential offensives against the New Hebrides, Fiji, Samoa, and New Caledonia.^[3][4]

The Allied plan to attack the southern Solomons was conceived by U.S. Navy Admiral Ernest King, Commander-in-Chief of the United States Fleet. King proposed the counter-offensive to deny the use of the southern Solomon Islands by the Japanese as bases to threaten the supply routes between the United States and Australia, and to use them as starting points for a campaign with the goal of isolating the new and major Japanese base at Rabaul while supporting the Allied New Guinea campaign. All of this had the eventual goal of opening the way for the U.S. to retake the Philippines.^[5] American Admiral Chester Nimitz, the Allied Commander-in-Chief for all forces in the Pacific, created the South Pacific theater of operations, with Vice Admiral Robert L. Ghormley placed in command on 19 June 1942, to direct the Allied offensive in the Solomons.^[6][7]

On 7 August 1942, the First Marine Division landed on Tulagi and Guadalcanal at Lunga Point, capturing the uncompleted Japanese airfield, and marking the first counter-offensive by the Allies in the Pacific Theater. The Allies continued construction on the airfield immediately using captured Japanese equipment. On 12 August, the airfield was renamed Henderson Field, for Major Lofton R. Henderson, killed during the Battle of Midway, the first Marine Corps pilot killed during the battle. By 18 August, Henderson Field was ready for operation.^[8]

Immediately after landing on Guadalcanal, Marines from the 1st Engineer Battalion worked around the clock utilizing captured Japanese heavy equipment to complete construction of the airfield. The first plane to land was a US Navy PBY Catalina that touched down on August 12 to assess the condition of the field. At that time the field was 2600ft long, good enough for fighters but still too short and soft for bombers. Three days later the first Seabee unit arrived possessing a Carryall which dramatically sped up construction. The field was declared ready for flight operations on August 18.^[9] As the first planes arrived, Henderson Field could barely be described as an airfield. It was an irregular blob cut out of the island growth, half-in and half-out of a coconut grove, with a short runway, and few revetments to protect the aircraft from shrapnel.^[10] Upon landing on Henderson Field on 4 September, Commanding Officer of Marine Aircraft Group 25, Colonel W. Fiske Marshall described the scene -- "looked like a Doré drawing of hell."^[11]

The runway was a northwest to southeast running, 2,400-foot (730 m) long gravel surface with an extra 1,000 feet (300 m) of Marston Mat frequently pockmarked with craters from Japanese artillery and naval gunfire. The strip was in such poor condition, it caused as many losses to aircraft as enemy action. In the heat, the field was a bowl of black dust which fouled the warplanes' engines.^[12] During rain, the airfield quickly turned muddy, miring planes in liquid muck. Major Marion Carl described it as "...the only place on Earth you could stand up to your knees in mud and still get dust in your eyes."^[13] The heavier SBD dive bombers had it the worst, since their hard rubber tires, designed for aircraft carrier landings and take-offs, ripped up the runways like plowshares. Wooden wheels were experimented with, but these did not fare any better.^[14] The runway was extended and widened several times during the long Guadalcanal campaign, and it was 3,800 feet (1,200 m) long and 150 wide by 4 September.^[15]

Henderson Field was also very close to the thinly-held lines of the U.S. First Marine Division, so security was always a concern. There were no fuel trucks, aircraft hangars, or repair buildings. Damaged aircraft were cannibalized for spare parts, and with no bomb hoists, all aircraft munitions had to be hand-loaded onto the warplanes. Fuel, always critically low, had to be hand pumped out of 55 gallon drums.^[13] After the arrival of fuel trucks, aviation gasoline still had to be hand-pumped into the trucks.^[14]

On 9 September 1942, the U.S. 6th Naval Construction Battalion (SeaBees) opened up a second runway about 1 mile (1.6 km) to the east of Henderson Field's original runway. This new runway, called "Fighter 1", consisted of tamped-down sod, and it was about 4,600 feet (1,400 m) long and 300 feet (91 m) wide. The Marine fighter squadrons operated out of Fighter 1, while the rest of the aircraft operating out of Henderson Field continued to use the original runway, referred to as "Bomber Field No. 1."^[15]

Henderson Field's facilities improved around 15 November, after it was officially a Marine Corps Air Base. Proper runways were installed using shipped-in ground-up coral, since the local coral was deemed rotten and slushy.^[16]

Living conditions on Guadalcanal were some of the most difficult faced by Marine aviation. Pilots and mechanics lived in mud-floored tents in a flooded coconut plantation called "Mosquito Grove." Most contracted tropical diseases such as malaria, dysentery, dengue fever, or fungal infections.^[17]

The misery was accompanied by mortal danger. The airfield was bombed nearly every day around noon by Mitsubishi G4M "Betty" bombers flying at 20,000 feet (6,100 m) in a perfect "Vee formation" escorted by fighter planes.^[18] It was frequently shelled as well, by Japanese artillery in the day and Japanese warships at night. The worst night of bombardment was on 13–14 October 1942—two Japanese battleships fired more than 700 heavy shells into Henderson Field, providing cover for the Japanese Navy's landing of Imperial Marines and army reinforcements further west on Guadalcanal. The bombardment killed six CAF pilots.^{[citation needed]}

From the time of the first Marine squadron landed on 20 August until 25 August, there was no commanding officer for Marine air, which instead reported directly to General Vandegrift. The Marines had not designated an air operations commander, the Army already had a squadron present and the field acquired the air of a naval base after they were promised to certain naval units. The first Marine commander was Colonel William W. Wallace, but he retained command temporarily.^[19][20] Cactus Air Force technically was under the command of Rear Admiral John S. McCain, who commanded all land based Allied aircraft in the South Pacific. Vandegrift and his operational commanders, however, exercised local command over the Allied aircraft operating out of Henderson Field.^[21]

On 3 September 1942, the fortunes of the beleaguered aviators changed with the arrival of Brigadier General Roy Geiger on board the first Marine Aircraft Group 25 plane to land on the island, an R4D Skytrain.^[22][23] As the "Commander, Aircraft, Guadalcanal" (ComAirCACTUS) and the 1st Marine Aircraft Wing, Geiger established his headquarters in a wooden Japanese pagoda on a hill about 200 yards (180 m) from the airfield. Through his energy, example, and sheer force of personality, he raised the collective spirits of the squadron's survivors. He was described as "...curt, cold, and some said ruthless....he was determined to squeeze the ultimate ounce of performance from men and machines".^[24] During his time in command, press-releases said there was a "sense of desperation but never defeatism,"^[25] Ultimately, the strain of command and harsh living conditions seriously fatigued, both mentally and physically, the 57-year-old Geiger. Geiger turned over the command on 7 November to his Chief of Staff, Brigadier General Louis E. Woods.^[26][27]

Brigadier Woods, a 21-year aviation veteran, commanded the Cactus fliers during the lowest point of the campaign. He quickly transformed from a "kindly colonel to a blood thirsty brigadier general."^[26] The day after Christmas, Woods turned the Cactus command to Brigadier General Francis P. Mulcahy, Commanding General of the 2nd Marine Aircraft Wing.^[28]

The majority of the Japanese aircraft engaged by the Cactus Air Force were from Imperial Japanese Navy air units. On 7 August, during the Guadalcanal campaign, 5th Air Attack Force, under Rear Admiral Sadayoshi Yamada, operated from Rabaul, New Britain, and Lae, Papua New Guinea, and were responsible for naval air operations in eastern New Guinea and the Solomon Islands. The 5th was a hybrid organization consisting of attached units from the 25th Air Flotilla, and reported to the 11th Air Fleet (also called the "Base Air Force"), under Nishizo Tsukahara. On the morning of 7 August, the 5th's air strength consisted of 39 fighters, 32 medium bombers, 16 dive bombers, and 17 seaplanes, including the 15 seaplane aircraft at Tulagi destroyed in the initial Allied air strikes during the landings on Tulagi and Guadalcanal.^[29][30]

The 5th's principal bomber unit was the 4th Air Group operating Mitsubishi G4M Type 1 "Betty" bombers. Twenty-four of the fighter aircraft in the 5th belonged to the Tainan Kōkūtai under Captain Masahisa Saito. The Tainan contained some of the top-scoring Japanese fighter aces, and flew the A6M2 Zero fighter. With 55 pilots and 24 aircraft, only the most experienced and able Tainan pilots were allowed to consistently participate in combat operations. The dive bombers (Aichi D3A1 "Vals") and the rest of the fighters (A6M3 Zeros) belonged to the 2nd Air Group. Most of the dive bombers were lost during the 7 and 8 August strikes on the Allied landing forces. Also on 7 and 8 August, the Misawa Air Group of the 6th Air Attack Force (also called the 26th Air Flotilla) under Vice Admiral Seigo Yamagata from Tinian with 27 Type 1 bombers joined the 5th Air Attack Force at Rabaul. Around the same time, Admiral Tsukahara moved from Tinian to Rabaul to supervise air operations against Allied forces around Guadalcanal.^[31]

The 4th and Misawa Air Groups took heavy losses during attacks on the Allied landing fleets off Guadalcanal on 7 and 8 August, losing 24 bombers and 153 crewmen killed while the Tainan Air Group lost four Zeros and four pilots. Until reinforcements could arrive, the 5th Air Attack Group was unable to continue attacking Marine positions on Guadalcanal, giving the U.S. time to prepare the captured airfield at Lunga Point uninterrupted by air attack. On 20 August 19, Type 1s from the Kisarazu Air Group of the 6th Air Attack Force arrived at Kavieng. On 2 September, ten Type 1s from the Chitose Air Group of the 24th Air Flotilla joined them at Kavieng. Both groups participated in subsequent bombing raids on Guadalcanal. Thirteen Zeros and pilots from the 6th Air Group joined the 2nd Air Group at Rabaul on 31 August, flying combat missions over Guadalcanal on 11 September.^[32][33]

From 1 October until the end of the war, the 11th Air Fleet was commanded by Jinichi Kusaka, also located at Rabaul. Some notable pilots flying with the 11th Air Fleet included Hiroyoshi Nishizawa and Junichi Sasai.

A force of Japanese seaplanes called the R-Area Air Force was created on 28 August under Rear Admiral Takatsugu Jojima, and operated from Rabaul as well as forward operating bases at Buin, the Shortland Islands, and Rekata Bay, Santa Isabel. The R-Area aircraft came from the four squadrons assigned to the Japanese seaplane tenders Kamikawa Maru, Chitose, Sanyo Maru, and Sanuki Maru. The R-Area Air Force mainly provided cover for Japanese convoys delivering troops and supplies to Guadalcanal, conducted reconnaissance missions around the Solomon Islands' area, and occasionally attacked Henderson Field. Also, air units from Japan's Combined Fleet's aircraft carriers, including Shōkaku, Junyō, Zuikaku, and Ryūjō, either operating from land bases with the 11th Air Fleet, or operating from the carriers, engaged Cactus Air Force aircraft during the Guadalcanal campaign.^[34]

U.S. Navy and Marine fighter pilots, with little high-altitude experience, were at a disadvantage because their F4F Wildcat was slower, heavier, less maneuverable, and a slow climber compared to the agile Japanese A6M Zero.^[61] The American pilots learned quickly to not dogfight the Zero. Instead, if they became engaged with one, they would give it a quick diving firing-burst, then dive away to regroup, climb, and attack again. Cactus pilots constantly refined their tactics and techniques, relying on teamwork in dogfights, improving their gunnery to remain effective against the Zero pilots.^[62]

Because of the Zero's maneuverability, American pilots quickly adapted hit-and-run tactics similar to those used by the American Flying Tigers in China and Burma.^[61] They also used a two-plane flight section, a technique developed by the U.S. Navy fighter pilots John Thach and Edward O'Hare, and dubbed the "Thach Weave." The two aircraft remained in the same general area, and, if Zeroes showed up, they had a better chance of engaging the aircraft on the tails of their wingmen.^{[citation needed]}

According to one American pilot, "One Zero against one Grumman is not an even fight, but with mutual support, two Grummans are worth four or five Zeros."^{[citation needed]}

The Wildcat had merits. It was well-protected compared to the lightly armored Zero, had a self-sealing fuel tank, and possessed adequate firepower with six .50-caliber M-2 Browning machine guns. U.S. Marine pilots, skeptical since the Battle of Midway, placed a great deal of confidence in their aircraft.^[14]

Because they could not effectively dogfight the Zeroes, Henderson Field's defenders could not gain air superiority to thwart Japanese attacks. They realized the best thing they could do was disrupt up each day's raid, whittle down the Japanese, then break-off to fight another day.^[63] With this in mind, their primary targets became the bombers rather than the fighters, and many of the tactics introduced were devised by Marine Major John L. Smith. The American pilots always sought to begin their attack at least 5,000 feet (1,500 m) above the Japanese formations, and they concentrated their attacks on trailing aircraft.^[14] This gave them good angles to shoot at the exposed fuel tanks of the Japanese bombers, and it presented a difficult gunnery problem for the bombers, since the high overhead passes of the American fighters put them into the blindspots of the Japanese gunners. This tactic also caused the escorting Japanese fighters to climb and burn more of their fuel, thus reducing their limited time over Guadalcanal.^[64]

From 3 September to 4 November 1942, the Cactus Air Force claimed 268 Japanese planes downed in aerial combat, and the damage inflicted on others is estimated to be as great.^{[citation needed]}

Because of the limited number of aircraft and fuel available during the early stages of the campaign, the CAF was unable to maintain a standing combat air patrol over Henderson Field. Therefore, CAF needed early warnings of incoming Japanese aircraft so their aircraft were in the air during Japanese air attacks.^[65] Members of the Australian Coastwatchers, including W. J. Read in northern and Paul Mason in southern Bougainville, Donald Kennedy on New Georgia, and Geoffrey Kuper on Santa Isabel relayed as Japanese airplane formations were heading for the island, giving the defenders on Guadalcanal time to get airborne.^[66][67] On 16 August, Lieutenant Commander Hugh A. Mackenzie of the Royal Australian Navy, the Deputy Staff Intelligence Officer for the British Solomon Islands Protectorate, established a radio station at Henderson Field to monitor coastwatcher transmissions and relay their warnings to the CAF.^[46] Admiral Bull Halsey said the coast-watchers "saved Guadalcanal".^{[citation needed]}

Several coastwatchers were stationed around Guadalcanal, including Martin Clemens (a local official for the British Solomon Islands Protectorate), Leif Schroeder, Donald Macfarlan, Ken Hay, and Ashton Rhoades. On August 14, Clemens entered the Marine lines at Lunga Point and et with General Vandegrift. The general placed him in charge of native administration and intelligence operations outside the Marine lines.^[68] These coastwatchers, with help from native Solomon Islanders, helped rescue and return several Allied pilots during the campaign.^[69]

The Cactus Air Force's dive bombers and torpedo planes sank or destroyed 17 large enemy vessels, including one Japanese battleship, one heavy cruiser (the Kinugasa), one light cruiser (the Yura), three destroyers (the Asagiri, Murakumo, and Natsugumo), and twelve transports, possibly sank three destroyers and one heavy cruiser, and heavily damaged 18 other ships, including one heavy cruiser and five light cruisers. The largest vessel was the battleship Hiei, which was finished off by the CAF, along with aircraft from the Enterprise, and B-17s from Espiritu, after being crippled by American cruisers and destroyers during the Naval Battle of Guadalcanal.^[58]

The fifteen Marine combat squadrons on Guadalcanal during this time suffered 94 pilots killed or missing-in-action, with another 177 evacuated with wounds or with sickness (especially severe malaria). Losses for Japanese aircraft during the Guadalcanal campaign are unknown.^[70] Japanese records show that several Marine and Army pilots were captured on Guadalcanal after being shot down over enemy-occupied jungle areas, but none of the pilots survived their captivity.^{[citation needed]}

Six aviators who served in the "Cactus Air Force" received the Medal of Honor for their actions during the Battle of Guadalcanal (August 1942 – February 1943):

• John L. Smith
• Robert E. Galer
• Joe Foss
• Harold W. Bauer
• Jefferson J. DeBlanc
• James E. Swett

All aviation units on Guadalcanal were subordinate to Commander, Aircraft, Guadalcanal (ComAirGuadal).

• Grumman F4F Wildcat
• Douglas SBD Dauntless
• Grumman TBF Avenger
• Grumman J2F-5 Duck
• Bell P-39 Airacobra
• Consolidated PBY Catalina
• Lockheed Hudson (RNZAF)

• AirSols
• Admiral Aubrey Fitch
• Marine Corps Early Warning Detachment, Guadalcanal (1942-43)
• Military history of the United States during World War II
• List of active United States Marine Corps aircraft squadrons
• List of United States Navy aircraft squadrons