The irony was that Yamamoto was not the worst of America’s enemies. He was no pacifist, but nor was he as militaristic as the hard-core Japanese hard-liners. Yamamoto opposed the 1940 alliance with Nazi Germany, which he feared would drag Japan into a ruinous war. While he didn’t oppose war as a means of saving Japan from a crippling U.S. oil embargo in 1941 (his depiction as a peacemonger in the movie Tora! Tora! Tora! is wrong), he did warn Japanese leaders that “in the first six to twelve months of a war with the United States and Great Britain, I will run wild and win victory upon victory. But then, if the war continues after that, I have no expectation of success.”

Some sixty-eight years before U.S. special forces killed Osama bin Laden, America conducted an assassination of another kind.

This time, the target wasn’t a terrorist. It was the Japanese admiral who planned the Pearl Harbor operation. But the motive was the same: payback for a sneak attack on the United States.

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In early 1943, Adm. Isoroku Yamamoto, commander in chief of the Japanese Navy, was one of the most hated men in America. He was seen as the Asian Devil in naval dress, the fiend who treacherously struck peaceful, sleeping America. And when the United States saw a chance for payback in April 1943, there was no hesitation. Hence a code name unmistakable in its intent: Operation Vengeance.

As with today’s drone strikes, the operation began with an intercepted message. Except it wasn’t a call from a cell phone, but rather a routine military radio signal. In the spring of 1943, Japan was in trouble: the Americans had captured Guadalcanal despite a terrible sacrifice of Japanese ships and aircraft. Stung by criticism that senior commanders were not visiting the front to ascertain the situation, Yamamoto resolved to visit naval air units on the South Pacific island of Bougainville.

As was customary, a coded signal was sent on April 13, 1943, to the various Japanese commands in the area, listing the admiral’s itinerary as well as the number of transport planes and fighter escorts in his party. But American codebreakers had been reading Japanese diplomatic and military messages for years, including those in the JN-25 code, used in various forms by the Imperial Navy throughout World War II. The Yamamoto signal was sent in the new JN-25D variant, but that didn’t stop American cryptanalysts from deciphering it in less than a day.

Adm. Chester Nimitz, the U.S. commander in the Pacific, authorized an operation to shoot down Yamamoto’s plane. With typical spleen, Pacific Fleet commander William “Bull” Halsey issued his own unambiguous message: “TALLY HO X LET’S GET THE BASTARD.”

Yet getting Yamamoto was easier said than done. Navy and Marine fighters like the F4F Wildcat and F4U Corsair didn’t have the range to intercept Yamamoto’s aircraft over Bougainville, four hundred miles from the nearest American air base on Guadalcanal. The only fighter with long enough legs was the U.S. Army Air Forces’ twin-engined Lockheed P-38G Lightning.

But even the P-38s faced a difficult task. To avoid detection, American planners wanted them to fly “at least 50 miles offshore of these islands, which meant dead-reckoning over 400 miles over water at fifty feet or less, a prodigious feat of navigation,” according to a history of the Thirteenth Fighter Command, the parent organization of the 339th Fighter Squadron that flew the mission.

Even worse, the Lightnings had no AWACS radar aircraft or land-based radar to guide them to the target, or even to tell them where Yamamoto’s plane was. Nor could the U.S. aircraft loiter over Bougainville in the midst of numerous Japanese fighter bases. They would essentially have to intercept Yamamoto where and when he was scheduled to be.

However, by calculating the speed of the Japanese G4M Betty bomber that would carry Yamamoto, probable wind speed, the enemy’s probable flight path, and assuming that Yamamoto would be as punctual as he was reputed to be, American planners estimated the intercept would occur at 9:35 a.m.

The Americans assigned eighteen P-38s for the mission, of which a flight of four would pounce on Yamamoto’s plane, while the remainder would climb above as top cover against Japanese fighters. Two Lightnings aborted on the way to Bougainville, leaving just sixteen to perform the mission.

That the Americans arrived just a minute early, at 9:34, was remarkable. Even more remarkable was that the Japanese appeared on time a minute later. Flying at 4,500 feet were two Betty bombers, one carrying Yamamoto and the other his chief of staff, Vice Admiral Matome Ugaki. They were escorted by six A6M Zero fighters keeping watch 1,500 feet above them.

Still undetected, twelve Lightnings climbed to eighteen thousand feet. The remaining four attacked the Bettys, with the first pair, flown by Capt. Thomas Lanphier Jr. and Lt. Rex Barber, closing in for the kill. As the two bombers dived to evade the interceptors, the American pilots couldn’t even be sure which one carried Yamamoto.

Lanphier engaged the escorts while Barber pursued the two bombers. Barber’s cannon shells and bullets slammed into the first Betty, an aircraft model notorious for being fragile and flammable. With its left engine damaged, it slammed into the jungle. Then the second Betty, attacked by three of the P-38s, crashed into the water. The Americans had lucked out again: the Betty that crashed into the jungle, killing its crew and passengers, had carried Yamamoto. From the Betty that hit the water, Admiral Ugaki survived (hours after Emperor Hirohito announced Japan’s surrender on August 15, 1945, Ugaki took off in a kamikaze and was never heard from again).

A Japanese search party hacked through the jungle until they found Yamamoto’s plane. “Afterward the Admiral’s body and the others were cremated and the ashes put into boxes,” recounts the Thirteenth Fighter Command history. “His cremation pit was filled, and two papaya trees, his favorite fruit, were planted on the mound. A shrine was erected, and Japanese naval personnel cared for the graves until the end of the war.”

Yamamoto’s remains were returned to Japan aboard the super battleship Musashi in May 1943 for a state funeral that drew a million mourners. For the Americans, euphoria and satisfaction were dogged by postwar controversy that lasted for sixty years over who actually shot down Yamamoto’s plane: Barber and Lanphier were credited with a half kill apiece, though many critics said Barber should have received full credit.

The irony was that Yamamoto was not the worst of America’s enemies. He was no pacifist, but nor was he as militaristic as the hard-core Japanese hard-liners. Yamamoto opposed the 1940 alliance with Nazi Germany, which he feared would drag Japan into a ruinous war. While he didn’t oppose war as a means of saving Japan from a crippling U.S. oil embargo in 1941 (his depiction as a peacemonger in the movie Tora! Tora! Tora! is wrong), he did warn Japanese leaders that “in the first six to twelve months of a war with the United States and Great Britain, I will run wild and win victory upon victory. But then, if the war continues after that, I have no expectation of success.”

Did Yamamoto’s death affect the war? His Pearl Harbor operation was audacious and brilliant, but his poor strategy at Midway six months later destroyed Japan’s elite aircraft carrier force (ironically, it was also U.S. codebreaking that set the stage for the Midway disaster). By 1943, he was a sick and exhausted man. Perhaps he might have come up with a better late-war naval strategy than the disastrous battles of the Philippine Sea and Leyte Gulf. Yet not even the architect of Pearl Harbor could save Japan from defeat.

Yamamoto’s assassination is still significant because it has been cited as a precedent for today’s drone strikes. To be clear, there is no doubt that assassinating Yamamoto was legal according to the laws of war. He was an enemy soldier in uniform, flying in an enemy military aircraft that was attacked by uniformed U.S. military personnel in marked military aircraft. This is nothing new. In 1942, British commandos unsuccessfully attempted to assassinate Rommel, and modern militaries devote great efforts to locating enemy headquarters to kill commanders and staffs.

But what’s really interesting is that compared with the controversy over today’s targeted assassinations, there was remarkably little fuss made over the decision to kill Yamamoto. The U.S. military treated it as a purely military matter that didn’t need civilian approval. Admiral Nimitz authorized the interception, and the orders were passed down the military chain of command. There was no presidential decision nor Justice Department review. It’s hard to imagine that the killing of a top Al Qaeda leader, let alone a top Russian, Chinese or North Korean commander, would be treated so routinely.