Action off Bougainville

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The Action off Bougainville was a naval and air engagement on the South Pacific Theater of World War II near Bougainville, Papua New Guinea on 20 February 1942. A United States Navy aircraft carrier task force on its way to raid the Imperial Japanese military base at Rabaul, New Britain was attacked by a force of land-based bombers of the Imperial Japanese Navy. The US task force was commanded by Admiral Wilson Brown and the Japanese aircraft forces were under the command of Eiji Gotō.

In the ensuing engagement, the Japanese air group lost 15 of 17 bombers sent to attack the American carrier group. The United States lost only two fighters in defence, and no ships were damaged. As a result of the loss of surprise, however, the Americans retired without raiding Rabaul as originally planned. Because of the heavy losses in bombers, the Japanese were forced to delay their planned invasion of New Guinea, giving the Allies more time to prepare defences against the Japanese advances in the South Pacific.


Following the capture of the port of Rabaul during the battle of Rabaul, Japanese forces proceeded to turn it into a major base. The allied command was concerned the fall of Rabaul threatened the San Francisco-Australia sea lane supply line and ordered the supply line to be patrolled. Admiral Chester William Nimitz and Admiral Brown devised a plan to solve the threat on the supply line by attacking the newly captured Rabaul. Task Force 11 (TF 11) and the ANZAC Squadron were tasked with undertaking the raid. Unfortunately, the ANZAC Squadron fuel oil supply was inadequate to accompany TF 11 to its launching point north-east of Rabaul for the planned 21 February air strike.


TF 11 with the carrier Lexington detected an unknown aircraft on radar 35 mi (30 nmi; 56 km) from the ship at 10:15 while still 450 mi (390 nmi; 720 km) from the harbour at Rabaul. A six-plane combat patrol was launched with two fighters directed to investigate the contact. These two planes, under command of Lieutenant Commander Thach, shot down a four-engined Kawanishi H6K4 "Mavis" flying boat about 43 mi (37 nmi; 69 km) out at 11:12. Two other planes of the combat patrol were sent to another radar contact 35 mi (30 nmi; 56 km) ahead, and shot down a second "Mavis" at 12:02. A third contact was made 80 mi (70 nmi; 130 km) out, but that plane reversed course and disappeared.

The Japanese search planes alerted Rabaul to the presence of US naval forces in the area. Vice Admiral Shigeyoshi Inoue, at the Imperial Japanese Fourth Fleet headquarters in Truk, ordered an initial air strike to be conducted from Rabaul; and ordered the heavy cruisers Aoba, Furutaka, Kinugasa, and Kako of cruiser Division 6 to intercept TF 11.

Seventeen Japanese Mitsubishi G4M1 "Betty" bombers of the 4th Kōkūtai took off from Vunakanau Aerodrome, Rabaul to attack TF 11. When Admiral Brown realised he had lost the element of surprise, he broke off the attack against Rabaul and started to retire from the area. A jagged vee signal was detected on air-search radar at 15:42. The contact was briefly lost, but reappeared at 16:25 47 mi (41 nmi; 76 km) west. Nineteen Grumman F4F-4 Wildcats from Lexington were sent to intercept the incoming targets. Five of the nine incoming "Betty"s from 2nd Chûtai of the 4th Kōkūtai,[1] were shot down.

A second formation of "Betty"s from 1st Chûtai of the 4th Kōkūtai were detected by radar at 16:49[2] completely unopposed, and only 12 mi (10 nmi; 19 km) out on the[3] disengaged side of the task force. Lexington had only two Wildcats left to confront the intruders. Lieutenants Marion Dufilho and Edward O'Hare flew eastward and arrived 1,500 feet (460 m) above eight "Bettys" 9 mi (7.8 nmi; 14 km) out at 17:00. Dufilho's guns jammed leaving only O'Hare to protect the carrier from the enemy flying very close together in V formation.

O'Hare employed a high-side diving attack accurately placing bursts of gunfire into a "Betty"'s right engine[4] and wing fuel tanks. When the stricken craft of Nitō Hikō Heisō Tokiharu Baba (3rd Shotai)[5] on the right side of the formation abruptly lurched to starboard, O'Hare ducked to the other side of the V formation and aimed at the enemy bomber of Ittō Hikō Heisō Bin Mori 3rd Shotai[5] on the extreme left. When O'Hare made his third and fourth firing passes, the Japanese planes were close enough to the American ships for them to fire their anti-aircraft guns. The five surviving "Betty"s managed to drop their ordnance, but all ten 551 lb (250 kg) bombs missed.[6] O'Hare's concentrated fire caused the leading Shōsa Takuzo Ito's "Betty"'s port engine nacelle to literally jump out of its mountings. O'Hare believed he had shot down five bombers, and damage a sixth. Lieutenant Commander John Thach arrived at the scene with other pilots of the flight and saw three of the enemy bombers falling in flames at the same time.[7]

O'Hare had destroyed only three "Betty"s: Nitō Hikō Heisō, Tokiharu Baba's from 3rd Shotai; Ittō Hikō Heisō, Susumu Uchiyama's (flying at left wing of the leading V, 1st Shotai); and the leader of the formation, Shōsa, Takuzo Ito's (flying on the head of leading V). Ito's left engine was hit at the time it dropped its ordnance. Its pilot Hikō Heisōchō Chuzo Watanabe[8] tried to hit Lexington with the damaged plane, but missed and flew into the water near Lexington at 17:12. Another two "Bettys" were damaged by O'Hare's attacks. Ittō Hikō Heisō Kodji Maeda (2nd Shotai, left wing of V) safely landed at Vunakanau aerodrome and Ittō Hikō Heisō Bin Mori was later shot down by Lieutenant Noel Gayler when trying to escape 40 mi (35 nmi; 64 km) from Lexington.[9]


As a result of the loss of surprise, Brown cancelled the planned raid on Rabaul and retired from the area. Because of the high losses in bomber aircraft, the Japanese postponed their impending invasion of Lae-Salamaua, Papua New Guinea from 3–8 March 1942.

Two "Mavis" flying boats were also shot down which were shadowing the US force, as well as two other Japanese scout aircraft lost in operational accidents while participating in the day's action. The US lost two fighters to defensive gunfire from the bombers, but one pilot survived, while no damage was inflicted on the US warships. US Navy pilot Edward O'Hare was awarded the Medal of Honor for his actions.



  1. ^ Shores, Cull, Izawa, pp. 186–188
  2. ^ Shores, Cull, Izawa, pp. 186–189
  3. ^ Ewing and Lundstrom 1987, p. 129.
  4. ^ Shores, Cull, Izawa, p. 189
  5. ^ a b Shores, Cull, Izawa, pp. 188–189
  6. ^ Shores, Cull, Izawa, p. 191
  7. ^ "Acepilots: Saving the Lexington"
  8. ^ Commanding officer Takuzo Ito wasn't piloting his own "Betty". The pilot was of lowest rank and the commander of the plane was an observer and/or navigator. That was common practice in the IJNAS.
  9. ^ Shores, Cull, Izawa, pp. 188–191