Admiral Yamamoto, commander of the Imperial Japanese Navy’s Combined Fleet, was the Harvard-educated, poker-playing mastermind of the December 7, 1941, attack.
On April 14, 1943, naval intelligence scored another code-breaking coup. The message began: “On April 18 CINC Combined Fleet will visit RXZ, R–, and RXP in accordance with the following schedule . . .” Adm. Isokoru Yamamoto was planning an inspection visit of Japanese bases in the upper Solomon Islands. The information immediately went from Commander in Chief Pacific Fleet Adm. Chester W. Nimitz
to Secretary of the Navy Frank Knox who delivered the news to President Franklin Roosevelt. Reportedly, the president’s response was, “Get Yamamoto.” Regardless of whether or not the president actually said those words, the order was given: kill the mastermind of the Pearl Harbor raid.
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.
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
Mitchell’s flight of four led the squadron at low altitude, with the killer flight, now consisting of Lanphier, Barber, and spares 1st Lt. Besby F. Holmes and 1st Lt. Raymond K. Hine, immediately behind. Mitchell, fighting off drowsiness, navigated by flight plan and dead reckoning. This proved to be the longest fighter-intercept mission of the war and was so skillfully executed by Mitchell that his force arrived at the intercept point one minute early, at 09:34, just as Yamamoto’s aircraft descended into view in a light haze. The P-38s jettisoned the auxiliary tanks, turned to the right to parallel the bombers, and began a full power climb to intercept them.
The tanks on Holmes’s P-38 did not detach and his element turned back toward the sea. Mitchell radioed Lanphier and Barber to engage, and they climbed toward the eight aircraft. The nearest escort fighters dropped their own tanks and dived toward the pair of P-38s. Lanphier, in a sound tactical move, immediately turned head-on and climbed towards the escorts while Barber chased the diving bomber transports. Barber banked steeply to turn in behind the bombers and momentarily lost sight of them, but when he regained contact, he was immediately behind one and began firing into its right engine, rear fuselage, and empennage. When Barber hit its left engine, the bomber began to trail heavy black smoke. The Betty rolled violently to the left and Barber narrowly avoided a mid-air collision. Looking back, he saw a column of black smoke and assumed the Betty had crashed into the jungle. Barber headed towards the coast at treetop level, searching for the second bomber, not knowing which one carried the targeted high-ranking officer.
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.
Lieutenant Hamasuna noted Yamamoto had been thrown clear of the plane’s wreckage, his white-gloved hand grasping the hilt of his katana sword, his body still upright in his seat under a tree. Hamasuna said Yamamoto was instantly recognizable, his head tilted down as if deep in thought. A post-mortem of Yamamoto’s body indicated two bullet wounds, one to the back of his left shoulder, and a separate bullet wound to his left lower jaw, that appeared to exit above his right eye. The Japanese navy doctor examining Yamamoto’s body determined the head wound killed Yamamoto. (These more violent details of Yamamoto’s death were hidden from the Japanese public, and the medical report whitewashed, this secrecy “on orders from above.
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.