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  G4M1 Model 11 Betty Manufacture Number ???? Tail 326
IJN
705 Kōkūtai

Pilot  FPO2/c Hiroshi Hayashi (survived)
Co-Pilot  Chief Flight Seaman Fumikatsu Fujimoto (KIA)
Radio  Flight Petty Officer Isamu Hachiki (KIA)
Radio  Flight Petty Officer Sukeichi Itoh (KIA)
Mechanic  Flight Petty Officer Nobuyuki Kuriyama (KIA)
Gunner  Chief Flight Seaman Keneyoshi Nomiyama (KIA)
Observer  FPO1/c Hiroaki Tanimura (KIA)
Passenger  Vice-Admiral Matome Ugaki, Chief of Staff, Combined Fleet (survived)
Passenger  Captain Motoharu Kitamura, Chief Paymaster, Combined Fleet (survived)
Passenger  Commander Rinji Tomoro, Meteorology Officer (KIA)
Passenger  Commander Kaoru Imananka, Staff Officer (KIA)
Passenger  Commander Suteji Muroi, Staff Officer (KIA)
Crashed  April 18, 1943 around 8:00am

Aircraft History
Built by Mitsubishi at Nagoya No. 3 Works. At the factory, painted with green upper surfaces and gray lower surfaces. The upper nose and each upper engine cowling was planted black. The leading edge of the inner wings had a yellow identification stripe. The fuselage Hinomaru was outlined with a white square. Delivered to the Imperial Japanese Navy (IJN) as G4M1 Model 11 Type 1 Attack Bomber manufacture number unknown (four digits).

Wartime History
During March 1943 or early April 1943 flown from Japan south to Truk then to Vunakanau Airfield near Rabaul. Assigned to the 705 Kōkūtai (705 Air Group) with tail code T1-326, later changed to 326 in white on both sides of the tail.

"Yamamoto Mission"
During Operation I-Go, Admiral Isoroku Yamamoto, Commander in Chief of the Combined Japanese Fleet and his senior staff planned an inspection tour of forward airfields and bases in the Shortlands and southern Bougainville. The purpose of this visit was to boost moral after the Japanese losses on Guadalcanal and thank the Japanese Army for cooperation.

On April 13, 1943 a coded Japanese message NTF131755 was sent to the commanders of Base Unit No. 1, 11th Air Flotilla and the 26th Air Flotilla with the planned itinerary and timetable. This message was encoded using the Japanese Naval Cipher JN-25D and was intercepted by three U.S. Magic stations and decoded by U.S. Navy cryptographers. Decoded, the message outlined Yamamoto's itinerary and timetable. According to the intercept, Yamamoto would depart "RR" Rabaul at 0600 in a medium attack plane [G4M1 Betty] and land at "RXZ" Ballale Airfield at 0800. Then, proceed by subchaser to "RXE" Shortland at 0840, then depart at 0945 aboard the same subchaser and return to Ballale at 1030, then depart at 1100 aboard G4M1 Betty and arrive at Buin Airfield (Kahili) at 1110. Finally at 1400 depart "RXP" Buin Airfield (Kahili) by G4M1 Betty and arrive back at Rabaul at 1540. All the times were in the Tokyo time zone used by the Imperial Japanese Navy (IJN). Local time was +1 hour ahead at Rabaul and +2 hours in the north Solomons.

On April 17, 1943 a secret plan dubbed "Operation Vengeance" was formulated and approved by Admiral Chester W. Nimitz. The interception mission was assigned to U.S. Army Air Force (USAAF) P-38G Lightnings from the 13th Air Force (13th AF), 339th Fighter Squadron (339th FS) and 70th Fighter Squadron (70th FS) that would require them to fly 435 miles over the open sea to intercept the bombers and kill Yamamoto and his senior staff before they landed, assuming they followed the intercepted itinerary and timetable. The mission would be the longest mission flown by land based fighters up to this point in World War II.

Mission History
On April 18, 1943 before dawn took off from Vunakanau Airfield near Rabaul piloted by FPO2/c Hiroshi Hayashi with co-pilot Chief Flight Seaman Fumikatsu Fujimoto with G4M1 Betty 2656 Tail 323. Both bombers flew eastward then landed at Lakunai Airfield pick up the senior staff passengers.

On the ground at Lakunai Airfield, five passengers boarded this aircraft including Vice-Admiral Matome Ugaki, Captain Motoharu Kitamura, Commander Rinji Tomoro, Commander Kaoru Imananka and Commander Suteji Muroi plus their baggage. Meanwhile, four passengers boarded G4M1 Betty 2656 Tail 323. including: Admiral Isoroku Yamamoto, Rear Admiral Rokurō Takata, Commander Kurio Toibana and Commander Noburu Fukusaki plus their baggage.

At 6:10am both bombers took off from Lakunai Airfield escorted by six A6M Zeros of the 204 Kōkūtai (204 Air Group) and the formation departed on schedule and proceeded as planned southeast and was scheduled to land at 8:00am at Ballale Airfield. The weather was described as fine with intermittent cumulus clouds.

Meanwhile, at 7:25am P-38 Lightnings of the 339th Fighter Squadron (339th FS) took off from Fighter 2 (Kukum) on Guadalcanal as part of Operation Peacock the top secret "Yamamoto Mission" to intercept and shoot down the Admiral's bomber. Each P-38 had two auxiliary fuel tanks for a six hundred mile round trip flight.

South of Empress Augusta Bay on Bougainville, they spotted the Japanese formation and the P-38s split up to engage the escorting A6M2 Zeros while the attack group engaged the bombers. Roughly a mile away, the P-38s were spotted by the Japanese formation, G4M1 Betty 2656 Tail 323 with passenger Admiral Isoroku Yamamoto dove to low altitude as a defensive maneuver and was followed by this Betty.

After the shoot down of G4M1 Betty 2656 Tail 323, this bomber was targeted by P-38G 42-12690 #100 pilot Holmes, P-38G pilot Hine and P-38G "Miss Virginia" 43-2204 Nose 147 pilot Barber. During the attack, Holmes dove at the bomber and opened fire causing the left engine to smoke. Next, attacked by Hine. Finally, Barber fired into the fuselage and claimed to cause it to explode.

In fact, this Betty was damaged but sucessfully ditched into the sea off Moila Point on southern Bougainville. Three survived and swam ashore: Vice-Admiral Matome Ugaki, Captain Motoharu Kitamura and Hiroshi Hayashi. The rest were killed in the air or died in the ditching. Later, the body of one of the crew washed ashore.

Credit for shooting down Ugaki's Betty
After the mission, Lanphier landed first and immediately claimed to have solely shot down Yamamoto's bomber. He was officially credited with the victory, before a post mission briefing was conducted or other pilots interviewed. Officially, the U.S. Air Force (USAF) credited Lanphier with 1 1/2 victories. Barber with 2 1/2 victories. Holmes with 1 1/2 victories. In fact, only the two bombers were shot down and no escorting Zeros were lost. Postwar research has definitively proven Lanphier's victory claim is incorrect and this bomber was shoot down solely by Rex Barber.

During the war, the news of the shoot down was suppressed in the United States, so as not to reveal that Japanese codes had been broken. Postwar research confirmed that Rex Barber actually shot down Yamamoto alone. This long standing controversy spawned a series of inquiries by several USAF credit review boards and the "Second Yamamoto Mission Association (SYMA)" to study the mission. But, officially, the USAF never changed the victory credit. Yet, Rex Barber is understood to be the sole pilot who shot down Yamamoto's Betty. This position was supported by the Second Yamamoto Mission Association, observations of the sole surviving Zero pilot, and even a letter Lanphier wrote to General Condon (claiming he shot down a bomber over the sea) and evidence from the bomber wreckage.

Fates of the Crew
Ashore, the three survivors were spotted by friendly forces and were taken to nearby Kahili (Buin).

Vice-Admiral Matome Ugaki was transported back to Japan and convalesced to recover from his injuries and blamed himself for Yamamoto's death. On August 15, 1945 after the Emperor made the radio annoucement that Japan would surrender, Ugaki noted in his personal diary that he had not yet received an official cease-fire order, and that as he alone was to blame for the failure of his aviators to stop the enemy and decided to fly a final mission himself to show the true spirit of bushido. His subordinates protested but he insisted, posed for pictures, removed his rank insignia and wore a Type 3 uniform (dark green) and carried a sword given to him by Admiral Yamamoto then boarded a D4Y Judy piloted by Warrant Officer Akiyoshi Endo. During the flight, Endo sent Ugaki's final radio message at 7:24pm reporting that the plane had begun its dive onto an American vessel, but was instead shot down by anti-aircraft fire or crashed into the sea.

Hiroshi Hayashi survived the Pacific War. As of 2005, lived in retirement on Yaku Sihima Island. Aside from an interiew with author Hiroyuki Agawa for The Reluctant Admiral (1979), Hayashi declines interviews from Japanese researchers and authors about his wartime service or this mission.

Wreckage
This Betty ditched into the seas roughly 100m off Moila Point on southern Bougainville. After the crash, the Japanese searched for the wreckage but only found small pieces in the area.

During April 2018, a team from Pacific Wrecks including Rod Pearce aboard MV Barbarian II attempted to search for this Betty using side scan sonar to survey the presumed ditching area, but were unable to locate the wreckage. Possibly, the wreckage was covered by sand over the decades or has otherwise disappeared.

References
Some sources state this plane was G4M1 manufacture number 2659 built Built by Mitsubishi No. 3 Works at Nagoya during March 1943 but this number is not listed in the Japanese Kodochosho (action report) or any known primary source.
Kodochosho, 705 Kōkūtai, April 18, 1943
13th Fighter Command "Fighter Interception Report" April 18, 1943
USAF Historical Study No. 85 USAF Credits For The Destruction of Enemy Aircraft, World War II [PDF] Alphabetical: Barber, Rex T. page 17 (PDF page 22) / Alphabetical: Holmes, Besby F. page 90 (PDF page 97)
The Reluctant Admiral (1979) by Hiroyuki Agawa pages 374-378
Fading Victory The Diary of Admiral Matome Ugaki, 1941-1945 (2008) pages 222-223, 330-331, 350-360 plus footnotes
13th Fighter Command in World War II (2004) Chapter 8 Yamamoto Mission by Jim Lansdale pages 137-162
Bureau of Aircraft Accidents Archives - Crash of Mitsubishi G4M off Moila Point "MSN: 2659 ?"
Thanks to Jim Lansdale for additional information

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Last Updated
April 18, 2023

Tech Info
Betty

SCUBA
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