4th Air Group
A land-based bomber formation of the Imperial Japanese Navy Air Service that fought in the Pacific during 1942.
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Overview
The 4th Air Group was a land-based bomber formation of the Imperial Japanese Navy Air Service during the Pacific War. Known in Japanese as Dai-Yon Kōkūtai, it was established on 10 February 1942 by combining one division from Chitose Air Group with two divisions from Takao Air Group. The constituent units brought experience from Japan’s Central Pacific operations and from the invasions of the Philippines and the Dutch East Indies. The newly assembled formation was equipped primarily with the Mitsubishi G4M Type 1 attack bomber, commonly known by the Allied reporting name Betty. The unit was created at a moment when Japanese forces were extending their control across the western and central Pacific. In February 1942 it moved to Rabaul on New Britain, an important Japanese base for operations against New Guinea and the surrounding seas. Initially subordinated to the 24th Air Flotilla, it transferred to the 25th Air Flotilla in April. From Rabaul, its aircraft conducted long-range bombing and maritime strike missions against Allied positions and naval forces, particularly around Port Moresby, Milne Bay, the Coral Sea, and Guadalcanal. One of the formation’s first major actions occurred on 20 February 1942, when it was ordered to attack a United States carrier force reported near Rabaul. Because torpedoes and fighter drop tanks had not reached the recently occupied base, the bombers were sent with conventional bombs and without effective fighter escort. Seventeen G4Ms took part. American carrier fighters and antiaircraft defenses destroyed most of the formation, including the aircraft carrying the group’s senior flying officer. The attack did not damage the carrier force and demonstrated the vulnerability of long-range bomber operations conducted beyond fighter-cover range. The 4th Air Group subsequently rebuilt its strength and mounted repeated attacks against Port Moresby from March through August. During the Battle of the Coral Sea on 7 May, twelve of its aircraft carried out a torpedo attack against Allied cruisers near Jomard Passage. The formation scored no confirmed hits and lost five aircraft. Its most severe losses came during the opening phase of the Guadalcanal campaign. On 7 August, following the Allied landings, twenty-seven bombers were redirected from a planned attack near Milne Bay to strike the beachhead at Lunga Point. The hurried mission used bombs rather than torpedoes and caused no significant damage while losing four aircraft. The following day, seventeen aircraft from the group joined nine bombers from Misawa Air Group in a torpedo attack against Allied shipping near Guadalcanal. Heavy antiaircraft fire and fighter interception destroyed most of the formation. Only a small number of badly damaged aircraft returned to Rabaul, and approximately 125 personnel were killed, including all of the officers leading the attack. The group continued attacks against Henderson Field and other targets during the early Guadalcanal campaign, but sustained losses that it could not easily replace. By late September 1942, after roughly seven months of combat, the formation was withdrawn from the Guadalcanal area. Its losses included two senior flying officers, six division commanders, more than forty aircrews, and over fifty aircraft. On 1 November 1942, the 4th Air Group was formally redesignated the 702nd Air Group. It therefore ceased to exist under its original designation, although its personnel and operational lineage continued within the Imperial Japanese Navy’s air organization.
History
The 4th Air Group was organized on 10 February 1942 within the Imperial Japanese Navy Air Service. Its formation brought together one division formerly associated with Chitose Air Group and two divisions from Takao Air Group. These components had served in different areas of Japan’s early-war expansion, including the Central Pacific, the Philippines, and the Dutch East Indies. The new unit operated the Mitsubishi G4M Type 1 attack bomber, a long-range twin-engine aircraft intended for both land-based bombing and anti-shipping missions. In February 1942 the group deployed to Rabaul, New Britain, where Japanese forces were building a major base complex for operations against New Guinea and the Southwest Pacific. It initially belonged to the 24th Air Flotilla and came under the 25th Air Flotilla from April. The unit’s first major engagement came on 20 February, after a flying boat reported an American carrier task force in the vicinity of Rabaul. Because aerial torpedoes and fighter drop tanks were not yet available at the newly captured base, seventeen bombers attacked with conventional bombs and lacked meaningful fighter escort. American F4F fighters and antiaircraft fire destroyed fifteen aircraft. The carrier was not hit, and the formation lost several senior leaders, including its flying commander. After receiving replacements, the group conducted recurring raids against Port Moresby between March and August. Its aircraft also took part in the Battle of the Coral Sea on 7 May, when twelve bombers attacked Allied cruisers near Jomard Passage with torpedoes. No hits were recorded and five aircraft were lost. These operations reflected the group’s role as a long-range strike formation, but they also exposed the operational difficulties of using heavily loaded bombers at the limits of their range, particularly when fighter escort, fuel infrastructure, or reliable intelligence was unavailable. The group’s most destructive period began with the Allied landings at Guadalcanal on 7 August. It had been preparing to attack an airfield near Milne Bay when the landing news arrived. Rather than reconfigure the aircraft for torpedo missions, commanders dispatched twenty-seven bombers with bombs against the beach near Lunga Point. The raid caused no significant damage and cost four aircraft. On the following morning, seventeen 4th Air Group bombers and nine from Misawa Air Group attacked the Allied fleet and transports with torpedoes. Antiaircraft fire broke up the formation, and surviving aircraft were attacked by carrier fighters on the withdrawal route. Only five severely damaged aircraft returned to Rabaul; approximately 125 men died, including all officers involved in leading the attack. The depleted formation continued to strike Henderson Field during the early Guadalcanal campaign. By late September, after seven months of operations, it had lost more than fifty aircraft, over forty aircrew members, two Hikōtaichōs, and six Buntaichōs. The group was withdrawn from the area and, on 1 November 1942, redesignated the 702nd Air Group. The redesignation ended the 4th Air Group’s separate identity, while its personnel and organizational continuity passed into the successor formation.
- 1942
Formation of the 4th Air Group
[1]The unit was established on 10 February by combining elements of Chitose and Takao Air Groups.
- 1942
Deployment to Rabaul
[1]The formation moved to Rabaul in February to support Japanese operations in the New Guinea and Southwest Pacific theaters.
- 1942
Attack on an American carrier force
[1]A 20 February bomber strike suffered extreme losses after being sent without effective fighter escort.
- 1942
Coral Sea operations
[1]The group conducted a torpedo attack near Jomard Passage on 7 May, losing five of twelve aircraft without confirmed hits.
- 1942
Guadalcanal operations
[1]The group participated in repeated attacks on the Allied beachhead and Henderson Field beginning in August.
- 1942
Redesignation as 702nd Air Group
[1]On 1 November, the unit was formally renamed the 702nd Air Group.
Products and positioning
A land-based naval aviation formation organized for long-range bombing and anti-shipping operations in the Pacific theater.
Military aircraft
Mitsubishi G4M Type 1 attack bomber
The group’s principal aircraft was the Mitsubishi G4M, a long-range land-based bomber used for conventional bombing and torpedo attacks. Its range made it useful for operations from Rabaul against distant targets, but missions were highly dependent on fuel availability, weather, intelligence, and fighter escort. The type was used during attacks around Port Moresby, the Coral Sea, and Guadalcanal.
Marketing campaigns
- 1942New Guinea campaign
New Guinea · Rabaul · Port Moresby
From Rabaul, the group conducted repeated bombing operations against Port Moresby and related Allied positions from March through August.
Outcome. The missions supported Japanese operations but generated substantial aircraft and aircrew losses.
- 1942Battle of the Coral Sea
Jomard Passage · Coral Sea
Twelve aircraft carried out a torpedo attack against Allied cruisers near Jomard Passage on 7 May.
Outcome. No hits were recorded and five aircraft were lost.
- 1942Guadalcanal campaign
Guadalcanal · Henderson Field · Lunga Point
The group attacked the Allied beachhead and later conducted frequent raids against Henderson Field during the campaign’s opening phase.
Outcome. The formation suffered catastrophic losses and was withdrawn in late September.
Brand decisions
1942
Bombing rather than torpedo attack at GuadalcanalStrategyBackground
After the Allied landing on 7 August, the group had been preparing a mission against an airfield near Milne Bay when the operational priority changed.
Action taken
Commanders sent twenty-seven bombers against the Lunga Point beachhead without taking time to replace bombs with torpedoes.
Aftermath
The raid achieved no significant hits and cost four aircraft; the following day’s torpedo mission produced far heavier losses.
1942
Redesignation as the 702nd Air GroupOtherBackground
After sustained losses during operations around New Guinea and Guadalcanal, the formation was reorganized within the naval air arm.
Action taken
The 4th Air Group was formally redesignated the 702nd Air Group on 1 November.
Aftermath
The original unit designation disappeared, while the successor formation continued the organizational lineage.
Sources4 sources
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