World War II: Operation Vengeance

Admiral Isoroku Yamamoto, Commander-in-Chief, Japanese Combined Fleet. Photograph Courtesy of the US Naval History & Heritage Command

During the Pacific conflict in World War II, American forces conceived a plan to get rid of Japanese commander Fleet Admiral Isoroku Yamamoto.

Date & Conflict

Operation Vengeance was conducted on April 18, 1943, during World War II (1939-1945).

Forces & Commanders




On April 14, 1943, Fleet Radio Unit Pacific intercepted message NTF131755 as part of project Magic. Having broken the Japanese naval codes, US Navy cryptanalysts decoded the message and found that it provided specific details for an inspection trip that the Commander-in-Chief of the Japanese Combined Fleet, Admiral Isoroku Yamamoto, intended to make to the Solomon Islands. This information was passed to Commander Ed Layton, the intelligence officer for the Commander-in-Chief of the US Pacific Fleet, Admiral Chester W. Nimitz.

Meeting with Layton, Nimitz debated whether to act on the information as he was concerned that it might lead the Japanese to conclude that their codes had been broken. He was also concerned that if Yamamoto was dead, he might be replaced with a more gifted commander. After much discussion, it was decided a suitable cover story could be devised to alleviate concerns regarding the first issue, while Layton, who had known Yamamoto before the war, stressed that he was the best the Japanese had. Deciding to move forward with intercepting Yamamoto's flight, Nimitz received clearance from the White House to move forward.


As Yamamoto was viewed as the architect of the attack on Pearl Harbor, President Franklin D. Roosevelt instructed Secretary of the Navy Frank Knox to give the mission the highest priority. Consulting with Admiral William "Bull" Halsey, Commander South Pacific Forces and South Pacific Area, Nimitz ordered planning to move forward. Based on the intercepted information, it was known that on April 18 Yamamoto would be flying from Rabaul, New Britain to Ballale Airfield on an island near Bougainville.

Though only 400 miles from Allied bases on Guadalcanal, the distance presented a problem as American aircraft would need to fly a 600-mile roundabout course to the intercept to avoid detection, making the total flight 1,000 miles. This precluded the use of the Navy and Marine Corps' F4F Wildcats or F4U Corsairs. As a result, the mission was assigned to the US Army's 339th Fighter Squadron, 347th Fighter Group, Thirteenth Air Force which flew P-38G Lightnings. Equipped with two drop tanks, the P-38G was capable of reaching Bougainville, executing the mission, and returning to base.

Overseen by the squadron's commander, Major John W. Mitchell, planning moved forward with the assistance of Marine Lieutenant Colonel Luther S. Moore. At Mitchell's request, Moore had the 339th's aircraft fitted with ship's compasses to aid in navigation. Utilizing the departure and arrival times contained in the intercepted message, Mitchell devised a precise flight plan that called for his fighters to intercept Yamamoto's flight at 9:35 AM as it began its descent to Ballale.

Knowing that Yamamoto's aircraft was to be escorted by six A6M Zero fighters, Mitchell intended to use eighteen aircraft for the mission. While four aircraft were tasked as the "killer" group, the remainder was to climb to 18,000 feet to serve as top cover to deal with enemy fighters arriving on scene after the attack. Though the mission was to be conducted by the 339th, ten of the pilots were drawn from other squadrons in the 347th Fighter Group. Briefing his men, Mitchell provided a cover story that the intelligence had been provided by a coastwatcher who saw a high ranking officer boarding an aircraft in Rabaul.

Downing Yamamoto

Departing Guadalcanal at 7:25 AM on April 18, Mitchell quickly lost two aircraft from his killer group due to mechanical issues. Replacing them from his cover group, he led the squadron west out over the water before turning north towards Bougainville. Flying at no higher than 50 feet and in radio silence to avoid detection, the 339th arrived at the intercept point a minute early. Earlier that morning, despite the warnings of local commanders who feared an ambush, Yamamoto's flight departed Rabaul. Proceeding over Bougainville, his G4M "Betty" and that of his chief of staff, were covered by two groups of three Zeros (Map).

Spotting the flight, Mitchell's squadron began to climb and he ordered the killer group, consisting of Captain Thomas Lanphier, First Lieutenant Rex Barber, Lieutenant Besby Holmes, and Lieutenant Raymond Hine to attack. Dropping their tanks, Lanphier and Barber turned parallel to the Japanese and began to climb. Holmes, whose tanks failed to release, turned back out to sea followed by his wingman. As Lanphier and Barber climbed, one group of Zeros dove to attack. While Lanphier turned left to engage the enemy fighters, Barber banked hard right and came in behind the Bettys.

Opening fire on one (Yamamoto's aircraft), he hit it several times causing it to roll violently to the left and plummet into the jungle below. He then turned towards the water seeking the second Betty. He found it near Moila Point being attacked by Holmes and Hines. Joining in the attack, they forced it to crash land in the water. Coming under attack from the escorts, they were aided by Mitchell and the rest of the flight. With fuel levels reaching a critical level, Mitchell ordered his men to break off the action and return to Guadalcanal. All of the aircraft returned except Hines' which was lost in action and Holmes who was forced to land in the Russell Islands due to a lack of fuel.


A success, Operation Vengeance saw the American fighters down both Japanese bombers, killing 19, including Yamamoto. In exchange, the 339th lost Hines and one aircraft. Searching the jungle, the Japanese found Yamamoto's body near the crash site. Thrown clear of the wreckage, he had been hit twice in the fighting. Cremated at nearby Buin, his ashes were returned to Japan aboard the battleship Musashi. He was replaced by Admiral Mineichi Koga.

Several controversies quickly brewed following the mission. Despite the security attached to the mission and the Magic program, operational details soon leaked out. This began with Lanphier announcing upon landing that "I got Yamamoto!" This breach of security led to a second controversy over who actually shot down Yamamoto. Lanphier claimed that after engaging the fighters he banked around and shot a wing off the lead Betty. This led to an initial belief that three bombers had been downed. Though given credit, other members of the 339th were skeptical.

Though Mitchell and the members of the killer group were initially recommended for the Medal of Honor, this was downgraded to the Navy Cross in the wake of the security issues. Debate continued over credit for the kill. When it was ascertained that only two bombers were downed, Lanphier and Barber were each given half kills for Yamamoto's plane. Though Lanphier later claimed full credit in an unpublished manuscript, the testimony of the lone Japanese survivor of the battle and the work of other scholars supports Barber's claim.

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Your Citation
Hickman, Kennedy. "World War II: Operation Vengeance." ThoughtCo, Aug. 26, 2020, Hickman, Kennedy. (2020, August 26). World War II: Operation Vengeance. Retrieved from Hickman, Kennedy. "World War II: Operation Vengeance." ThoughtCo. (accessed February 2, 2023).