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Who2 Biography:

Isoroku Yamamoto

, Sailor / Military Leader / World War II Figure

  • Born: 4 August 1884
  • Birthplace: Nagaoka, Japan
  • Died: 18 April 1943 (shot down by U.S. forces)
  • Best Known As: Japanese admiral who planned the attack on Pearl Harbor

Name at birth: Isoroku Sadayoshi

Isoroku Yamamoto studied at Harvard from 1919 to 1921, and returned to the United States in 1925 on a diplomatic mission. He didn't want to go to war with the United States, but when called upon by his country Yamamoto planned the sneak attack on Pearl Harbor and then led the Japanese navy to its early victories in World War II. When the U.S. decoded a Japanese message in 1943 that included Admiral Yamamoto's itinerary, they ambushed his plane in the south Pacific and killed him.

Extra credit: Yamamoto lost two fingers on his left hand during the Battle of Tsushima in 1905.

 
 
Military History Companion: Adm Isoroku Yamamoto

Yamamoto, Adm Isoroku (1884-1943). Yamamoto first saw action in the Russo-Japanese war, when a modern Japanese fleet destroyed an obsolete Russian one at Tsushima (1905), and where he lost a finger. He subsequently served in Europe and the USA, first as naval attaché in Washington (1925) and then as a participant in the London naval conferences of 1930 and 1934-5, getting to know his future enemies well. Returning to Japan as deputy minister for the navy between 1936 and 1939, he strove to modernize his own navy, building a balanced fleet of battleships and carriers but also landing craft and transports for amphibious operations in a future Pacific war. C-in-C of the imperial Japanese fleet from 1940, he is best remembered as the architect and executor of the surprise attack at Pearl Harbor on 7 December 1941. By failing to sink any US carriers at this time he opened the way for the defeat at Midway, but as he knew, Japan could never have won the Pacific campaign against a fully mobilized US war economy. He was the victim in April 1943 of the world's first mid-air assassination, when US fighters, acting on decryption of Japanese naval signals shot down his plane over Bougainville in the Solomon Islands.

— Peter Caddick-Adams

 

(1884–1943), Japanese admiral and champion of naval aviation; as Combined Fleet commander in chief (1941), carried out the air

No Imperial Japanese Navy officer of his age knew more about the United States than Yamamoto. He had served as a language officer and special student at Harvard (1919–21) and as naval attaché in Washington (1926–28). When navy vice minister (1936–39), Yamamoto opposed Japan's alignment with Germany and Italy, warning that the United States was not the weak‐willed nation pictured by Tokyo's hard‐liners. He also warned fellow officers that the industrial might of America posed a great threat. But when he was ordered to fight the United States, he took bold action.

The orthodox strategy of the Japanese naval General Staff was to wait for the U.S. Fleet to steam into the western Pacific and destroy it there in a battleship contest. To Yamamoto, a pioneer of naval aviation and a long‐standing lover of games of chance, this was a weak‐hearted approach. He insisted on a preemptive carrier strike on Pearl Harbor to destroy the U.S. Fleet at the outset. The navy staff opposed him, and only his immense moral stature allowed him to prevail.

The attack on 7 December 1941 proved a brilliant tactical success, and strategically it achieved its objective of protecting Japan's Southeast Asian offensives. But the wave of American public anger that it aroused made impossible a limited settlement of the war. Yamamoto continued to command the fleet in 1942 and 1943, but less successfully. The disastrous Japanese defeat at the Battle of Midway was his responsibility, and his air offensives in the Solomons wore down Japanese naval airpower relentlessly. On 18 April 1943, Yamamoto was on his way to visit forward units in the Solomon Islands when his plane was shot down by U.S. P‐38s, alerted to his route by reading the Japanese naval codes.

[See also MAGIC; World War II, U.S. Naval Operations in: The Pacific.]

Bibliography

  • Hiroyuki Agawa, The Reluctant Admiral. Yamamoto and the Imperial Navy, 1979.
  • Shinjimbutsu Oraisha, Yamamoto Isoroku no subete, 1985
 
US Military Dictionary: Isoroku Yamamoto

Yamamoto, Isoroku (1884-1943) Japan's greatest naval strategist in World War II, and the naval officer who conceived of the surprise attack on the U.S. naval base at Pearl Harbor in 1941. He graduated from the naval academy in 1904, fought in the Russo-Japanese War, and served as naval attaché in the Japanese embassy in Washington, D.C. (1926-1927). In little more than ten years he rose quickly through the ranks, becoming vice minister of the Japanese navy in 1936, commander of Japan's First Fleet in 1938, and commander in chief of Japan's Combined Fleet in August 1941. Yamamoto opposed war with the United States, but, once the decision had been made, he argued that the only way to win such a war was a surprise attack that would completely disable the U.S. naval forces in the Pacific. (He also predicted that, should the war with the United States last longer than a year, Japan would lose.) After the successful attack on Pearl Harbor, Yamamoto wanted a decisive battle with the remainder of the U.S.'s Pacific forces (its aircraft carriers), but Japan lost that battle, at Midway in June 1942. His next campaign, in the Solomon Islands, was also unsuccessful, and he died when the U.S. forces shot down his plane over Bougainville Island in the Solomons.

See the Introduction, Abbreviations and Pronunciation for further details.

 
Biography: Isoroku Yamamoto

Yamamoto Isoroku (1884-1943) was Commander-in-chief of combined Japanese fleet, who was Japan's greatest naval strategist in World War II.

Yamamoto Isoroku, "the Nelson of the Japanese navy," was originally born Takano Isoroku, sixth son of an impoverished schoolteacher, Takano Teikichi, and his second wife Mineko, on April 4, 1884. Isoroku belonged to the Echigo clan, an old tough warrior people who had resisted the unification of Japan under the Meiji emperor. His father gave him the name Isoroku (meaning 56 in Japanese) as he was that age when his son was born in the small village of Kushigun Sonshomura on a bleak northern island that produced many Japanese sailors. Soon after his birth, his father became headmaster of the primary school in the nearby market town of Nagaoka.

At age 16, after taking competitive examinations, Isoroku enrolled in the Naval Academy at Etajima, off the shore of Hiroshima. There he spent three years, combining study with rigorous physical training. After that, he spent a year on a square-rigged windjammer. Graduating in 1904 as seventh in his class, he fought against Russia's Baltic Fleet at Tsushima, a strait between Japan and Korea, in an engagement recognized by historians as "one of the most decisive naval actions in history." As an ensign on the cruiser Nisshin, part of the protective screen for Admiral Togo Heihachiro's flagship Mikasa, Isoroku saw closeup the tactics of one of the world's greatest admirals. From Togo, he learned one thing above all: the need for surprise in battle. In a letter to his family, the young seaman described a major mishap:

When the shells began to fly above me I found I was not afraid. The ship was damaged by shells and many were killed. At 6:15 in the evening a shell hit the Nisshin and knocked me unconscious. When I recovered I found I was wounded in the right leg and two fingers of my left hand were missing. But the Russian ships were completely defeated and many wounded and dead were floating on the sea.

Between 1904 and the outbreak of World War I, Isoroku went on training cruises to Korea and China, traveled to the west coast of the United States, and toured every major port in Australia. In 1913, he was sent to the Naval Staff College at Tsukiji, a prerequisite for high command. Upon graduation in 1916, he was appointed to the staff of the Second Battle Squadron.

That same year, at age 30, Isoroku - now a lieutenant commander - was adopted by the wealthy and socially prestigious Yamamoto family. Such adoptions were a common practice in Japan: families lacking a male heir sought to keep the lineage from dying out. As Isoroku's parents had died several years earlier, he felt he could accept the Yamamoto's generous invitation. At a formal ceremony in a Buddhist temple, he took on the family name, which means "Base of the Mountain."

At age 30, Yamamoto married Reiko Mihashi, daughter of a dairy farmer from his own province and a woman who bore him four children. Although he engaged in intensive Buddhist meditation, he made no secret of his relationships with "ladies of the night." A talented calligrapher, he would decorate the geisha houses of his past and current mistresses, and lived far beyond his means, earning a second income from his skill at bridge and poker. He once said, "If I can keep 5,000 ideographs in my mind, it is not hard to keep in mind 52 cards."

In April of 1919, Yamamoto began two years of study at Harvard University, where he concentrated on the oil industry - the lifeblood of any modern navy. Returning with the rank of commander in July of 1921, he was appointed instructor at the naval staff college in Tokyo. In June of 1923, he became captain of the cruiser Fuji.

Yamamoto received his first major command when in September of 1924 he was sent to the new air-training center at Kasumigaura, 60 miles northeast of Tokyo, where at age 40 he took flying lessons. Within three months, he was director of studies. Yamamoto's handpicked pilots became an élite corps, the most sought-after arm of the Japanese navy. From January of 1926 to March of 1928, he was naval attaché to the Japanese embassy in Washington, there to investigate America's military might.

Historian Gordon W. Prange describes Yamamoto at the height of his powers as:

a man short even by Japanese standards (five feet three inches), with broad shoulders accentuated by massive epaulets and a thick chest crowded with orders and medals. But a strong, commanding face dominates and subdues all the trappings. The angular jaw slants sharply to an emphatic chin. The lips are full, cleancut, under a straight, prominent nose; the large, well-spaced eyes, their expression at once direct and veiled, harbor potential amusement or the quick threat of thunder.

The year 1928 saw him briefly serving with the naval general staff and commanding the light cruiser Isuzu and the carrier Akagi. He was then appointed to the navy ministry's naval affairs bureau, where he was an innovator concerning air safety and navigation. In 1930, Yamamoto served as a special assistant to the Japanese delegation to the London Naval Conference; made rear admiral, he was instrumental in raising the Japanese quota level for light cruisers to 70 percent of American and British forces. From December of 1930 to October of 1933, he headed the technical section of the navy's aviation bureau, and from December of 1935 to December of 1936, he was chief of the bureau itself. Here he directed the entire naval air program - carriers, seaplanes, and land-based craft.

All this time, Yamamoto fought for naval parity with the other great sea powers. For example in 1934, when another naval conference was held in London, Yamamoto - now vice admiral and chief delegate - firmly rejected any further extension of the 5-5-3 ratio. This quota, established at the Washington Conference of 1921-22, had limited Japanese building of heavy warships to 60 percent of American and British construction. Calling the existing ratio a "national degradation," he demanded full equality, using the analogy of a diplomatic dinner party: "I was never told there that being much shorter than the others I ought to eat only three-fifths of the food on my plate. I ate as much as I needed."

During the attempted putsch of February 26, 1936, an effort to topple Japan's parliamentary government in favor of direct military rule, junior officers at the admiralty asked Yamamoto to join the rebels. He immediately ordered them to return to their desks, to which they responded without a murmur.

In December of 1936, Yamamoto was made vice minister of the Japanese navy and hence was firmly placed in Japan's policymaking élite. He accepted the post reluctantly, for he loved air command and hated politics. In office, he did the expected: promoted the development of aircraft carriers. At the same time, he vainly opposed the construction of new battleships, claiming that they could be sunk by torpedo planes. Yamamoto quoted an old Japanese proverb, "The fiercest serpent may be overcome by a swarm of ants," then elaborated: "These [battle]ships are like elaborate religious scrolls which old people hung up in their homes. They are of no proved worth. They are purely a matter of faith - not reality."

While in office, he took several courageous stands. He opposed army desires for an alliance with Germany, fearing that such an agreement would lead to war with the United States and Britain, the world's two strongest naval powers, and possibly the Soviet Union. Moreover, he noted, the Imperial Navy and indeed the entire Japanese economy depended on imports of raw materials from the United States. In 1937, he opposed Japan's invasion of China, telling a friend, "The stupid army has started again." On December 12, 1937, Japanese planes bombed the U.S. gunboat Panay, cruising China's Yangtse River. Three Americans were killed, and 43 were injured. Yamamoto personally apologized to U.S. Ambassador Joseph C. Grew, saying, "The Navy can only hang its head."

Such views made Yamamoto unpopular and like Admiral Yonai Mitsumasa, Japan's navy minister, he became a target for extremist attacks. The atmosphere became so hostile that tanks and machine guns were installed in the Navy Ministry. Supposedly, extreme rightists offered 100,000 yen as reward for his assassination.

On August 30, 1939, two days before Hitler invaded Poland, Yamamoto was appointed commander-in-chief of the combined fleet. Holding the rank of full admiral, he was operational head of Japan's entire navy; it was the highest honor the Japanese fleet could bestow. In addition, Yonai later said, "It was the only way to save his life - send him off to sea."

When on September 27, 1940, Japan signed the Tripartite Pact with Germany and Italy, Yamamoto warned Premier Konoye Fumimaro concerning possible war with the United States:

If I am told to fight regardless of the consequences, I shall run wild for the first six months or a year, but I have utterly no confidence for the second or third year. The Tripartite Pact has been concluded and we cannot help it. Now that the situation has come to this pass, I hope you will endeavor to avoid a Japanese-American war.

That October, he privately described the nature of the next war by saying:

As I see it, naval operations of the future will consist of capturing an island, then building an airfield in as short a time as possible - within a week or so - moving up air units, and using them to gain air and surface control over the next stretch of the ocean. Do you think we have the kind of industrial capacity to do that?

Already Yamamoto was thinking in terms of bold, almost reckless, strikes. During fleet maneuvers in the spring of 1940, in noting the achievements of carrier-based planes, he thought that an attack on the American fleet, stationed at Pearl Harbor, Hawaii, might be possible, and immediately presented his plan to Fukudome Shigeru, chief of staff of the combined fleet. At the end of July of 1941, Yamamoto said to the commander of the submarine fleet: "If we fight both Britain and America we will be defeated… . If war comes, our only chance is to destroy the fleet at Pearl Harbor and send submarines to the west coast of America."

On July 25, 1941, U.S. President Franklin D. Roosevelt froze Japanese assets in retaliation for its occupation of southern Indochina, a move that severed all trade between the two nations. Now Japan's ever-precious supply of oil was cut off, causing it to seek domination of the petroleum-rich Dutch East Indies and to risk war with the United States and Britain. In late September, Yamamoto visited Admiral Nagano Osami, chief of the naval general staff, to dissuade him from pursuing military plans made on September 6 to fight the United States. If war, however, was truly inevitable, Japan - Yamamoto said - should scrap traditional plans centering on lying in wait for the American battle fleet and ambushing it near Japan itself. Rather than allow a U.S. build-up, Japan must make a preemptive strike, crippling the American navy at the outset of the conflict. Such a move could shift the strategic balance in Japan's favor, protect the all-important southern flank in southeast Asia, and hopefully lead to a negotiated peace.

Yamamoto's plan eventually called for a massive air strike involving all six large carriers of the First Air Fleet; they had to approach within 200 miles of Hawaii without being discovered. Writes his biographer John Dean Potter:

The plan was his - and his alone… . He had supervised the smallest detail, perfected it, fought single-handed past the opposition of every senior admiral, offered to lead it personally from the bridge of the leading carrier - and finally threatened to resign if it were not approved.

In October 1941, Nagano gave his reluctant approval. On December 1, Japan's highest decision-making body, the Imperial Conference, decided upon war with the United States, Britain, and the Netherlands. Emperor Hirohito personally issued the orders to Yamamoto: "You must be determined to meet our expectations by exalting our force and authority throughout the world by annihilating the enemy." Aboard his flagship Yamato, stationed in Japan's Inland Sea, Yamamoto gave the coded attack orders to his strike force: "Climb Mount Niitaka," a reference to a peak in Formosa that was the highest point in the Japanese empire.

On December 7, the greatest air operation the world had yet seen took place - Yamamoto's famous strike on Pearl Harbor. In a single blow, 353 planes from six aircraft carriers almost completely destroyed the U.S. Pacific Fleet; 18 American ships were sunk or disabled as were nearly 200 planes; 2,335 servicemen and 68 civilians were killed. Commander Genda Minoru recommended a second strike, seeking to hit two American aircraft carriers and undamaged fuel tanks on Oahu. Admiral Nagumo Chuichi, the task force's leader, refused. A second strike, he reasoned, would be pressing one's luck and furthermore the Japanese carriers were needed for major offensives in Southeast Asia. Nagumo was a torpedo expert and lacked the needed imagination for such an operation; he had only been given carrier command because he was a senior admiral.

Rear Admiral Kuroshima Kameto immediately sought to overrule Nagumo by ordering a search for the American carriers, but Yamamoto replied: "[Nagumo] may have information we do not have. He must fight his own battle. I have complete faith in him." When his operations officer wanted to transfer Nagumo, Yamamoto responded: "How can I? He is an old-fashioned samurai type. If I move him he will commit hari-kiri because he will consider it such a disgrace."

Because of such restraint, Rear Admiral Edwin T. Layton, a leading U.S. staff officer, can write: "Pearl Harbor may have been a disaster, but it was a long way from being the knockout blow that Yamamoto had intended." Furthermore, by sinking so many battleships and thereby forcing the United States to adopt carrier warfare, Yamamoto had inadvertently contributed to American victory.

Yamamoto was always uneasy about his success, ever possessing a curious fatalism. He wrote a friend: "The fact that we have had a small success at Pearl Harbor is nothing…. Personally I do not think it is a good thing to whip up propaganda to encourage the nation. People should think things over and realize how serious the situation is." To win, he warned, "We would have to march into Washington and sign the treaty in the White House."

On February 27-28, 1942, the battle of Java Sea took place. Fought on both sides entirely by cruisers, it was the biggest surface engagement since Jutland. The Japanese defeated a combined force of Dutch, British, and American ships, thereby enabling Japan to seize oil-rich Java. Yamamoto now had sufficient oil to keep his fleet afloat in the foreseeable future.

Yamamoto anticipated that the United States might attempt a carrier raid on Tokyo. Believing that it was his foremost duty to protect the Imperial City, and the emperor in particular, he established a picketboat line extending over a 1,000-mile front some 600 to 700 miles east of Japan. He also ordered naval aircraft to engage in long-range patrols. On April 18, 1942, some 700 miles from Japan, 16 B-25 bombers from the U.S. carrier Hornet headed for Tokyo. Soon Lieutenant Colonel James H. Doolittle was bombing the Japanese capital as well as such neighboring cities as Yokohama, Kawasaki, and Yokosuka. Although the damage was relatively slight, Yamamoto was shocked, regarding it as a mortifying personal defeat. Writes biographer Potter, noting how impulsive the admiral suddenly became: "There can be no doubt however that his normally clear judgment was warped by the Doolittle raid."

From May 4-8, 1942, the world's first major carrier engagement took place in the Coral Sea. Entirely fought by aircraft, it was the first sea battle in history in which no warship of either side ever saw an enemy craft. The Japanese sought to take Port Moresby in New Guinea, thereby cutting off Australia from Allied aid. Tactically, the battle was a Japanese victory, for they had sunk the carrier Lexington and two smaller warships. Yet Japan lost the carrier Shoho, saw severe damage to the carrier Shokaku, and experienced the loss of most of the Zuikaku's planes. The Japanese commander, Vice Admiral Inouye Shigeyoshi, deprived of most of his striking power in aircraft, withdrew. His failure to pursue the damaged Yorktown drew Yamamoto's ire, though Inouye had little choice. Strategically, the Coral Sea marked a U.S. victory because the Japanese abandoned plans to occupy Port Moresby and attack Australia. Furthermore, Yamamoto was served notice that despite U.S. numerical inferiority, the Japanese fleet was not invincible.

Seeking retribution for the Doolittle raid, Yamamoto decided to draw out what was left of the U.S. Pacific Fleet in a decisive battle. The capture of Midway Island, a coral atoll six miles in diameter and a U.S. base just 1,136 miles from Hawaii, would give Japan an advanced outpost for air and submarine patrols. Furthermore, so Yamamoto believed, the strike would draw out the fullest strength of the U.S. Pacific Fleet. He would establish a lethal ambush, one that would destroy the carriers that had escaped him at Pearl Harbor. Once Midway was seized, Hawaii would be invaded, forcing the U.S. to sue for peace. Conversely, Yamamoto believed that if Japan did not soon engage in a decisive sea battle, its defeat was simply a matter of time. In a sense, Midway was his last chance.

Yamamoto assembled the largest fleet in the history of Japanese naval warfare - some 260 ships, among them 11 battleships, 8 carriers, 22 cruisers, 65 destroyers, and 21 submarines. Also involved were some 700 planes and 100,000 naval personnel.

On the surface, Yamamoto's strategy was extremely sophisticated, perhaps too much so. He divided his fleet into widely separated groups. A northern force, including two carriers, would capture Kiska and Attu, islands at the western end of the Aleutians. This strike would not only divert attention from the main target, Midway, it would keep American forces from using the islands as stepping stones to Japan. (He planned to withdraw Japanese forces from the islands before the grueling winter). The bombing of Dutch Harbor would cause even further diversion. An advance force of Japanese submarines, patrolling west of Hawaii, would warn of any U.S. craft in the vicinity, sinking such ships before they could defend Midway. Twenty-four hours after the Aleutian strike, Admiral Nagumo's striking force of four large carriers would hit Midway from the northwest, followed the next day by Vice Admiral Kondo Nobutake's second fleet of two battleships, a small aircraft carrier, half a dozen heavy cruisers, and an invasion convoy. As the main strength of the American fleet lay in Hawaiian or Australian waters (so the Japanese believed), the strike on Midway would be a complete surprise.

Once Midway was captured, the remnants of the U.S. fleet would be forced to attempt its rescue. But by then the Japanese would have the advantage of position as well as at least a 2:1 advantage in carriers and four to five times the number of screening vessels. At that point, Yamamoto himself would lead the combined fleet's main force, a powerful unit of seven battleships that included the two largest in the world then or since: his flagship Yamato and her sister ship, the Musashi. While he would be shutting the jaws of a gigantic trap, the northern force would come from the Aleutians to cut off the U.S. line of retreat. Notes Layton:

His intricate battle choreography also required that his opponents move according to predicted positions; one false step or foreknowledge of the plan could throw the entire operation into disarray.

In the battle, which took place from June 4 to 6, 1942, Yamamoto operated under many disadvantages. Thanks to American cryptographers, the Japanese sailed into a trap. Some Japanese ships had even mentioned their destination by name, and on May 20 a lengthy order of Yamamoto himself was intercepted. By the last week of May, the United States knew the date, place, and time of operation, as well as the composition of the Japanese forces. Yamamoto's submarines were ordered to report on the presence of American carriers, but they arrived on station 25 minutes too late to do so. Yamamoto's operations officer had information pointing to the presence of a powerful U.S. carrier force, but failed to inform Admiral Nagumo. By maintaining radio silence on his flagship, Yamamoto was unable to give instructions when needed. Not a single senior admiral had been fully briefed; all were drawn into combat on the shortest of notice. Nagumo failed to order an immediate attack once he learned of U.S. ships in the vicinity, thereby dooming his force to destruction.

In the ensuing battle, no surface ships sighted each other or exchanged gunfire. The devastating exchanges were carried out entirely by aircraft at long ranges. Three American carriers unexpectedly appeared, the Enterprise, Hornet, and Yorktown - the last ship fresh from hasty repairs. Within ten minutes, they sank three Japanese carriers - Kaga, Akagi, and Soryu - that comprised close to half of Japan's entire carrier tonnage. The remaining Japanese carrier Hiryu successfully sunk the Yorktown, but later in the day it was hit by the Enterprise.

A particularly crucial turning point took place when Nagumo, having learned that his initial air strike did not succeed in critically damaging Midway, decided to use his reserve planes in a second strike. While his carrier crews were in the act of changing from torpedoes to bombs, his force found itself suddenly exposed to the carrier-based planes of the U.S. Pacific Fleet.

Yamamoto himself took no part in the battle until it was too late. He wanted to engage the Americans with his battleships, and in a desperate move sought the daylight bombing of Midway. Yet not being able to bring his scattered groups together on time, he feared further losses and withdrew. Only 307 Americans died compared to 3,500 Japanese. Henceforth, Japan fought on the defensive. Writes military historian Ronald H. Spector: "For the Japanese, Midway was an ill-conceived, sloppily executed operation." One commentator finds it the most decisive battle since Trafalgar, another the Stalingrad of the Pacific.

Even if conquered by Japan, Midway would have been difficult to hold. It would remain an exposed salient (line of defense), subject to frequent bombing. Although the Japanese were able to conquer Kiska and Attu without real opposition, neither island possessed strategic value. The loss of an undamaged Zeke-Zero fighter in a feint on Dutch Harbor enabled the United States to design the sturdier and more powerful F6F Hellcat.

Yamamoto never fully recovered from the shock of this defeat, although he soon commanded air offensive in the Solomons campaign. Noting the strategic importance of Guadalcanal, he realized that the establishment of an American base there challenged his domination of the South Pacific. Engaging in a war of attrition to dislodge U.S. marines who started landing on August 7, 1942, Yamamoto's fleet suffered huge losses of aircraft and pilots. After major efforts, he realized that his destroyer transports, called the "Tokyo Express," could not remove the Americans. Finally, on January 4, 1943, he ordered the evacuation of that island's 13,000 Japanese troops; doing so was one of the great tactical successes of the war. He confessed to an old classmate: "I do not know what to do next."

In an effort to build morale, Yamamoto decided to make inspection trips throughout the South Pacific. In particular, he wanted to thank troops recovering from their ordeal on Guadalcanal. At age 59, he was tired, weary of war, and of life itself: "I have killed quite a few of the enemy, and many of my own men have been killed. So I believe the time has come for me to die too." During the Guadalcanal conflict, his hair had turned snowy-white.

In April 1943, U.S. intelligence intercepted advance reports of Yamamoto's tour. Eighteen American Lightning planes were waiting for the first attempt in history to ambush an enemy commander-in-chief in the air. On the 18th, his aircraft, under the escort of nine zeroes, was shot down by a P-38 near Kahili in southern Bougainville. On June 5, the admiral's ashes were honored in Tokyo in full state ceremony, a tribute accorded only once before - on the exact same day in 1934 to Admiral Togo.

Further Reading

Agawa, Hiroyuli. The Reluctant Admiral: Yamamoto and the Imperial Navy. Translated by John Bester. Kodansha International, 1979.

Hoyt, Edwin B. Yamamoto: The Man Who Planned Pearl Harbor. McGraw-Hill, 1990.

Potter, John Dean. Yamamoto: The Man Who Menaced America. Viking, 1965.

Evans, David C., ed. and trans. The Japanese Navy in World War II: In the Words of Former Naval Officers. Naval Institute Press, 1986.

Prange, Gordon W., Donald M. Goldstein, and Katherine V. Dillon. At Dawn We Slept: The Untold Secret of Pearl Harbor. McGraw-Hill, 1981.

- . Miracle at Midway. McGraw-Hill, 1982.

Spector, Ronald H. Eagle Against the Sun: The American War with Japan. Free Press, 1985.

Toland, John. The Rising Sun: The Decline and Fall of the Japanese Empire, 1936-1945. Random House, 1970.

 

(born April 4, 1884, Nagaoka, Japan — died April 18, 1943, Solomon Islands) Japanese naval officer. He fought in the Russo-Japanese War and thereafter rose to become commander in chief of Japan's Combined Fleet in 1939. When it was decided to go to war with the U.S., Yamamoto asserted that the only chance for a Japanese victory lay in a surprise attack that would cripple U.S. naval forces in the Pacific and conceived of the surprise attack on Pearl Harbor. He then sought to destroy the remnants of the U.S. fleet, principally its aircraft carriers, but the Japanese lost the resulting Battle of Midway in June 1942. His campaign in the Solomon Islands was also unsuccessful. He was killed when the U.S. (which had broken the Japanese communications codes) discovered his whereabouts and shot down his plane over Bougainville Island.

For more information on Yamamoto Isoroku, visit Britannica.com.

 
Columbia Encyclopedia: Yamamoto, Isoroku
(ēsō'rōkū' yämä'mōtō) , 1884–1943, Japanese admiral in World War II. He headed the combined fleet in 1941 and was the mastermind behind Japan's attack on Pearl Harbor. After he was killed in action in 1943, he became a national hero. Throughout his career he worked to build an integrated air-surface arm for the navy.

Bibliography

See H. Hagawa, The Reluctant Admiral (1982).

 
Wikipedia: Isoroku Yamamoto
Isoroku Yamamoto
4 April 1884April 18 1943 (aged 59)
Isoroku_Yamamoto.jpg

Fleet Admiral (Admiral of the Fleet) Isoroku Yamamoto
Place of birth Nagaoka, Niigata, Japan
Place of death Solomon Islands
Allegiance Empire of Japan
Service/branch Naval_Ensign_of_Japan.svg Imperial Japanese Navy
Years of service 1901–1943
Rank Fleet Admiral,
Commander-in-Chief
Unit Combined Fleet among others
Commands Kitakami
Isuzu
Akagi
Naval Air Command
Navy Ministry
Naval Air Command
1st Fleet
Combined Fleet
1st Battleship Division[1]
Battles/wars Russo-Japanese War
World War II (Battle of Midway)
Awards Grand Cordon of the Supreme Order of the Chrysanthemum
Grand Cordon of the Order of the Rising Sun Paulownia Blossoms,
Grand Cordon of the Order of the Sacred Treasure,
Order of the Golden Kite (1st class),
Order of the Golden Kite (2nd class),
Knight's Cross of the Iron Cross with Oak Leaves and Swords[1]
This is a Japanese name; the family name is Yamamoto.

Fleet Admiral Isoroku Yamamoto (Japanese: 山本五十六 Yamamoto Isoroku?) (4 April 188418 April 1943) was Commander-in-Chief of the Combined Fleet during World War II, graduate of Imperial Japanese Naval Academy and an alumnus of U.S. Naval War College and Harvard University (1919–1921).

Yamamoto held several important posts in the Imperial Japanese Navy, and undertook many of its changes and reorganizations, especially its development of naval aviation. He was the commander-in-chief during the decisive early years of the Pacific War and so was responsible for major battles such as Pearl Harbor and Midway. He died during an inspection tour of forward positions in the Solomon Islands when his transport aircraft was ambushed by American P-38 Lightning fighter planes. His death was a major blow to Japanese military morale during World War II.

Family background

Yamamoto was born as Isoroku Takano in Nagaoka, Niigata. His father was Sadayoshi Takano, a lower-ranking samurai of Nagaoka-Han. "Isoroku" is an old Japanese term meaning "56"; the name referred to his father's age at Isoroku's birth.

In 1916, Isoroku was adopted into the Yamamoto family and took the Yamamoto name. It was a common practice for Japanese families lacking sons to adopt suitable young men in this fashion to carry on the family name. In 1918, Isoroku married a woman named Reiko with whom he had four children: two sons and two daughters.

Early career

After graduating from the Imperial Japanese Naval Academy in 1904, Yamamoto served on the cruiser Nisshin during the Russo-Japanese War. He was wounded at the Battle of Tsushima, losing two fingers (the index and middle fingers) on his left hand. He returned to the Naval Staff College in 1914, emerging as a lieutenant commander in 1916.

Preparing for war, 1920s and 1930s

Fleet Admiral Isoroku Yamamoto
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Fleet Admiral Isoroku Yamamoto

Yamamoto was a political dove who was fundamentally opposed to war with the United States by virtue of his studies at Harvard University (1919–1921), his tour as an admiral's aide, and his two postings as a naval attaché in Washington, D.C. He was promoted to captain in 1923. In 1924, at the age of 40, he changed his specialty from gunnery to naval aviation. His first command was the cruiser Isuzu in 1928, followed by the aircraft carrier Akagi. Yamamoto was a strong proponent of naval aviation, and (as vice admiral) served as head of the Aeronautics’ Department before accepting a post as commander of the First Carrier Division.

He participated in the second London Naval Conference of 1930 as a rear admiral and the 1934 London Naval Conference as a vice admiral, as the government felt that a career military specialist needed to accompany the diplomats to the arms limitations talks. Yamamoto personally opposed the invasion of Manchuria in 1931, the subsequent land war with China (1937), and the Tripartite Pact (1940) with Nazi Germany and Fascist Italy. As Deputy Navy Minister, he apologized to United States Ambassador Joseph C. Grew for the bombing of the gunboat USS Panay in December 1937. These issues made him a target of assassination by pro-war militarists.

Rank insignia (Admiral) of Isoroku Yamamoto
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Rank insignia (Admiral) of Isoroku Yamamoto

Throughout 1938, many young army and naval officers began to speak publicly against Yamamoto and certain other Japanese admirals such as Yonai and Inouye for their strong opposition towards a Tripartite pact with Nazi Germany and for reportedly being against "Japan's natural interests."[2] Yamamoto himself received a steady stream of hate mail and death threats from Japanese nationalists but his reaction to the prospect of death by assassination was passive and accepting. The Admiral wrote:

To die for Emperor and Nation is the highest hope of a military man. After a brave hard fight the blossoms are scattered on the fighting field. But if a person wants to take a life instead, still the fighting man will go to eternity for Emperor and country. One man's life or death is a matter of no importance. All that matters is the Empire. As Confucius said, "They may crush cinnabar, yet they do not take away its color; one may burn a fragrant herb, yet it will not destroy the scent." They may destroy my body, yet they will not take away my will.[3]

The Japanese army, annoyed at admiral Yamamoto's unflinching opposition to a Rome-Berlin-Tokyo treaty, dispatched military police to "guard" Yamamoto; this was an attempt by the Army to keep an eye on him.[4] He was later reassigned from the Navy Ministry to sea as the Commander-in-Chief of the Combined Fleet on (30 August 1939). This was done as one of the last acts of the then acting Navy Minister Mitsumasa Yonai, under Baron Hiranuma's short-lived administration partly to make it harder for assassins to target Yamamoto; Yonai was certain that if Yamamoto remained ashore, he would be killed before the year (ie. 1939) ended.[5] Yamamoto was promoted to full admiral on 15 November 1940.

Yamamoto's career promotions


When General Hideki Tojo was appointed Prime Minister on October 18 1941, many political observers thought that Yamamoto's career was essentially over. Tojo had been Yamamoto's old opponent from the time when the latter served as Japan's deputy navy minister and Tojo was the prime mover behind Japan's takeover of Manchuria. It was believed that Yamamoto would be appointed to command the Yokosuka Naval Base, "a nice safe demotion with a big house and no power at all."[6] After the new Japanese cabinet was announced the next day, however, Yamamoto found himself left alone in his position as Full admiral despite his open conflicts with General Tojo and other members of the Army's oligarchy who favoured war with the European powers and America. Two of the main reasons for Yamamoto's political survival was his immense popularity within the navy fleet where he commanded the respect of his men and officers respectively as well as his close relations with the royal family.[7] Emperor Hirohito, like Yamamoto, shared a deep respect for the West. A third reason was probably the acceptance by Japan's naval hierarchy that:

there was no officer more competent to lead the Combined Fleet to victory than Admiral Yamamoto. His daring plan for the Pearl Harbor attack had passed through the crucible of the Japanese naval establishment, and after many expressed misgivings, his fellow admirals had realized that Yamamoto spoke no more than the truth when he said that Japan's hope for victory in this [upcoming] war was limited by time and oil. Every sensible officer of the navy was well aware of the perennial oil problems. Also, it had to be recognized that if the enemy could seriously disturb Japanese merchant shipping, then the fleet would be endangered even more."[8]

Consequently, Yamamoto stayed in his post. But with General Tojo now in charge of Japan's highest political office, it became clear that the Army would lead the Navy into a war about which Yamamoto had serious resevations:


Should hostilities once break out between Japan and the United States, it is not enough that we take Guam and the Philippines, nor even Hawaii and San Francisco. We would have to march into Washington and sign the treaty in the White House. I wonder if our politicians (who speak so lightly of a Japanese-American war) have confidence as to the outcome and are prepared to make the necessary sacrifices.[9]

Nevertheless, Yamamoto accepted the reality of impending war and planned for a quick victory by destroying the US fleet at Pearl Harbor while simultaneously thrusting into the oil and rubber resource rich areas of Southeast Asia--especially the Dutch East Indies, Borneo and Malaya. In naval matters, Yamamoto opposed the building of the super-battleships Yamato and Musashi as an unwise investment of resources.

Yamamoto was responsible for a number of innovations in Japanese Naval Aviation. Although remembered for his association with aircraft carriers due to Pearl Harbor and Midway, Yamamoto did more to influence the development of land-based naval aviation, particularly the G3M and G4M medium bombers. His demand for great range and the ability to carry a torpedo was intended to conform to Japanese conceptions of attriting the American fleet as it advanced across the Pacific in war. The planes did achieve long range, but long-range fighter escorts were not available. These planes were lightly constructed and when fully fueled, they were especially vulnerable to enemy fire. This earned the G4M the sardonic nick-name "the Flying Cigarette Lighter." Yamamoto would die in one of these aircraft.

The range of the G3M and G4M contributed to a demand for great range in a fighter aircraft. This partly drove the requirements for the A6M Zero which was as noteworthy for its range as for its maneuverability. Both qualities were again purchased at the expense of light construction and flammability that later contributed to the A6M's high casualty rates as the war progressed.

Fleet Admiral Yamamoto, U.S. file photo
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Fleet Admiral Yamamoto, U.S. file photo

As Japan moved toward war during 1940, Yamamoto gradually moved toward strategic as well as tactical innovation, again with mixed results. Prompted by talented young officers such as Minoru Genda, Yamamoto approved the reorganization of Japanese carrier forces into the First Air Fleet, a consolidated striking force that gathered Japan's six largest carriers into one unit. This innovation gave great striking capacity, but also concentrated the vulnerable carriers into a compact target; both boon and bane would be realized in war. Yamamoto also oversaw the organization of a similar large land-based organization in the 11th Air Fleet, which would later use the G3M and G4M to neutralize American air forces in the Philippines and sink the British Force "Z".

In January 1941, Yamamoto went even further and proposed a radical revision of Japanese naval strategy. For two decades, in keeping with the doctrine of Captain Alfred T. Mahan,[10] the Naval General Staff had planned in terms of Japanese light surface forces, submarines and land-based air units whittling down the American Fleet as it advanced across the Pacific until the Japanese Navy engaged it in a climactic "Decisive Battle" in the northern Philippine Sea (between the Ryukyu Islands and the Marianas Islands), with battleships meeting in the traditional exchange between battle lines.

Correctly pointing out this plan had never worked even in Japanese war games, and painfully aware of American strategic advantages in military productive capacity, Yamamoto proposed instead to seek a decision with the Americans by first reducing their forces with a preemptive strike, and following it with a "Decisive Battle" sought offensively, rather than defensively. Yamamoto hoped, but probably did not believe, if the Americans could be dealt such terrific blows early in the war, they might be willing to negotiate an end to the conflict. As it turned out, however, the note officially breaking diplomatic relations with the United States was delivered late, and he correctly perceived the Americans would be resolved upon revenge and unwilling to negotiate. Yamamoto's thoughts on this matter were later dramatically encapsulated in the apocryphal "sleeping giant" quote uttered in the movie Tora! Tora! Tora!.

The Naval General Staff proved reluctant to go along and Yamamoto was eventually driven to capitalize on his popularity in the fleet by threatening to resign to get his way. Admiral Osami Nagano and the Naval General Staff eventually caved in to this pressure, but only insofar as approving the attack on Pearl Harbor. Surprise attacks have a long military tradition when starting a war, and Japan could see clear to supporting such to give themselves six months to secure the resources of the Netherlands East Indies without the interference of the American navy.

The First Air Fleet commenced preparations for the Pearl Harbor Raid, solving a number of technical problems along the way, including how to launch torpedoes in the shallow water of Pearl Harbor and how to craft armor-piercing bombs by machining down battleship gun projectiles.

References: Evans & Peattie (1997), Peattie (2002).

The Attack on Pearl Harbor, December 1941

As Yamamoto had planned, the First Air Fleet of six carriers armed with about 390[citation needed] planes, commenced hostilities against the Americans on 7 December 1941, launching 350 of those aircraft against Pearl Harbor in two waves. The attack was a complete success according to the parameters of the mission which sought to sink at least four American battleships and prevent the U.S. Fleet from interfering in Japan's southward advance for at least six months. American aircraft carriers were also considered a choice target, but were not prioritized ahead of battleships.[citation needed]

In the end, five American battleships were sunk, three damaged, and eleven other cruisers, destroyers and auxiliaries were sunk or seriously damaged. The Japanese lost only 29 aircraft, but suffered damage to more than 111 aircraft. The damaged aircraft were disproportionately dive- and torpedo-bombers, seriously impacting available firepower to exploit the first two waves' success and First Air Fleet Commander Vice Admiral Chuichi Nagumo withdrew. Yamamoto later lamented Nagumo's failure to seize the initiative to seek out and destroy the American carriers, absent from the harbor, or further bombard various strategically important facilities on Oahu. Nagumo had absolutely no idea where the American carriers might be, and remaining on station while his forces cast about looking for them ran the risk his own force might be found first and attacked while his aircraft were absent searching. Further, his aircraft also lacked appropriate ordnance for attacking the machine tools and drydocks of the shipyard, or even the revetted fuel tanks, whose destruction could have been more serious losses than the fighting ships themselves. In any case, insufficient daylight remained after recovering the aircraft from the first two waves for the carriers to launch and recover a third before dark, and Nagumo's escorting destroyers lacked the fuel capacity for him to loiter long. Much has been made of Yamamoto's hindsight and wishful thinking, but it is instructive to note he did not punish Nagumo in any way for his withdrawal, which was, after all, according to plan, and the prudent course to take.

On the political level, the attack was a disaster for Japan, rousing American passions for revenge due to it being a "sneak attack". In fact, the Japanese had begun all their modern wars in this fashion and it was fully expected they would do so again — just not at Pearl Harbor. The shock of the attack coming in an unexpected place, with such devastating results and without the expected "fair play" of a declaration of war galvanized the American public's determination to avenge the attack. When asked by Prime Minister Fumimaro Konoe in mid-1941 concerning the outcome of a possible war with the United States, Yamamoto made a well known and prophetic statement: If ordered to fight, "I shall run wild considerably for the first six months or a year but I have utterly no confidence for the second and third years."[11] His prediction would be vindicated as Japan easily conquered territories and islands for the first 6 months of the war until it suffered a shattering defeat at the Battle of Midway on June 4-7, 1942 which tilted the balance of power in the Pacific towards the U.S. and allowed America to initiate offensive operations against Japan at Guadalcanal.

As a strategic blow intended to prevent American interference in the Netherlands East Indies for six months, the attack was a success, but unbeknownst to Yamamoto, it was a pointless one. The U.S. Navy had abandoned any intention of attempting to charge across the Pacific towards the Philippines at the outset of war in 1935 (in keeping with the evolution of War Plan Orange). In 1937, the U.S. Navy had further determined even fully manning the fleet to wartime levels could not be accomplished in less than six months, and myriad other logistic assets needed to execute a trans-Pacific movement simply did not exist and would require two years to construct after the onset of war. In 1940, U.S. Chief of Naval Operations, Admiral Harold Stark had penned "Plan Dog", which emphasized a defensive war in the Pacific while the U.S. concentrated on defeating Nazi Germany first, and consigned Admiral Husband Kimmel's Pacific Fleet to merely keeping the IJN out of the eastern Pacific and away from the shipping lanes to Australia.

As a tactical raid, the attack was an overall victory, handily achieving some objectives while only losing 29 aircraft and five miniature submarines. Strategically, it was a failure, as the American people were not crushed morally, but rather galvanized them to seek out full revenge.

References: Evans & Peattie (1997), Miller (1991), Peattie (2002).

Six months of victories, December 1941 to May 1942

Japan's Aggressor: Admiral Yamamoto, photomechanical print on paper.Time Magazine, December 22, 1941.
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Japan's Aggressor: Admiral Yamamoto, photomechanical print on paper.Time Magazine, December 22, 1941.

With the American Fleet largely neutralized at Pearl Harbor, Yamamoto's Combined Fleet turned to the task of executing the larger Japanese war plan devised by the Imperial Japanese Army and Navy General Staff. The First Air Fleet proceeded to make a circuit of the Pacific, striking American, Australian, Dutch and British installations from Wake Island to Australia to Ceylon (now Sri Lanka) in the Indian Ocean. The 11th Air Fleet caught the American 5th Air Force on the ground in the Philippines hours after Pearl Harbor, and then proceeded to sink the British Force "Z" (battleship HMS Prince of Wales and battlecruiser HMS Repulse) underway at sea.

Under Yamamoto's able subordinates, Vice Admirals Ozawa, Kondo and Takahashi, the Japanese swept the inadequate remaining American, British, Dutch and Australian naval assets from the Netherlands East Indies in a series of amphibious landings and surface naval battles that culminated in the Battle of the Java Sea on 27 February 1942. With the occupation of the Netherlands East Indies, and the reduction of the remaining American positions in the Philippines to forlorn hopes on the Bataan Peninsula and Corregidor island, the Japanese had secured their oil- and rubber-rich "Southern Resources Area".

Having achieved their initial aims with surprising speed and little loss (albeit against enemies ill-prepared to resist them), the Japanese paused to consider their next moves. Since neither the British nor the Americans were willing to negotiate, their thoughts turned to securing and protecting their newly seized territory, and acquiring more with an eye toward additional conquest and/or attempting to force one or more of their enemies out of the war.

Competing plans were developed at this stage, including thrusts to the west against India, the south against Australia and the east against the United States. Yamamoto was involved in this debate, supporting different plans at different times with varying degrees of enthusiasm and for varying purposes, including "horse-trading" for support of his own objectives.

Plans included ideas as ambitious as invading India or Australia, as well as seizing Hawaii. These grandiose ventures were inevitably set aside as the Army could not spare enough troops from China for the first two, nor shipping to support the latter two. (Shipping was allocated separately to IJN & IJA, and jealously guarded.[12]) Instead, the Imperial General Staff supported an Army thrust into Burma in hopes of linking up with Indian Nationalists revolting against British rule, and attacks in New Guinea and the Solomon Islands designed to imperil Australia's sea line of communication with the United States. Yamamoto agitated for an offensive Decisive Battle in the east to finish the American fleet, but the more conservative Naval General Staff officers were unwilling to risk it.

In the midst of these debates, the Doolittle Raid struck Tokyo and the surrounding areas, galvanizing the threat posed by the American aircraft carriers in the minds of staff officers, and giving Yamamoto an event he could exploit to get his way. The Naval General Staff agreed to Yamamoto's Midway (MI) Operation, subsequent to the first phase of the operations against Australia's link with America, and concurrent with their own plan to seize positions in the Aleutian Islands.

Yamamoto rushed planning for the Midway and Aleutians missions, while dispatching a force under Rear Admiral Takeo Takagi, including the Fifth Carrier Division (the large, new carriers Shōkaku and Zuikaku), to support the effort to seize the islands of Tulagi and Guadalcanal for seaplane and airplane bases, and the town of Port Moresby on Papua New Guinea's south coast facing Australia.

The Port Moresby (MO) Operation proved an unwelcome reverse. Although Tulagi and Guadalcanal were taken, the Port Moresby invasion fleet was compelled to turn back when Takagi clashed with an American carrier task force in the Battle of the Coral Sea in early May. Although the Japanese sank the American carrier Lexington in exchange for a smaller carrier, the Americans damaged the carrier Shōkaku so badly that she required dockyard repairs. Just as importantly, Japanese operational mishaps and American fighters and anti-aircraft fire devastated the dive bomber and torpedo plane elements of both Shōkaku’s and Zuikaku’s air groups. These losses sidelined Zuikaku while she awaited replacement aircraft and aircrews, and saw to tactical integration and training. These two ships would be sorely missed a month later at Midway.

References: Dull (1978), Evans & Peattie (1997), Lundstrom (1984), Parillo.

The Battle of Midway, June 1942

Main article: Battle of Midway

Yamamoto's plan for the MI was an extension of his efforts to knock the U.S. Pacific Fleet out of action long enough for Japan to fortify her defensive perimeter in the Pacific island chains. Yamamoto felt it necessary to seek an early, offensive decisive battle.

This was long believed to have been to draw American attention—and possibly carrier forces—north from Pearl Harbor by sending his Fifth Fleet (two light carriers, five cruisers, 13 destroyers and four transports) against the Aleutians, raiding Dutch Harbor on Unalaska Island and invading the more distant islands of Kiska and Attu. Recent scholarship[13] using Japanese language documents has revealed it was, rather, an unrelated venture of the Naval General Staff which Yamamoto agreed to conduct concurrently with the Midway operation, in exchange for the latter's approval.

While Fifth Fleet attacked the Aleutians, First Mobile Force (4 carriers, 2 battleships, 3 cruisers, and 12 destroyers) would raid Midway and destroy its air force. Once this was neutralized, Second Fleet (1 light carrier, 2 battleships, 10 cruisers, 21 destroyers, and 11 transports) would land 5,000 troops to seize the atoll from the American Marines.

The seizure of Midway was expected to draw the American carriers west into a trap where the First Mobile Force would engage and destroy them. Afterward, First Fleet (1 light carrier, 7 battleships, 3 cruisers and 13 destroyers), in conjunction with elements of Second Fleet, would mop up remaining American surface forces and complete the destruction of the Pacific Fleet.

To guard against mischance, Yamamoto initiated two security measures. The first was an aerial reconnaissance mission (Operation K) over Pearl Harbor to ascertain if the American carriers were there. The second was a picket line of submarines to detect the movement of the American carriers toward Midway in time for First Mobile Force, First Fleet, and Second Fleet to combine against it. In the event, the first was aborted and the second delayed until after American carriers had sortied.

The plan was a compromise and hastily prepared, but appeared well thought out, well organized, and finely timed when viewed from a Japanese viewpoint. Against four carriers, two light carriers, 11 battleships, 16 cruisers and 46 destroyers likely to be in the area of the main battle the Americans could field only three carriers, eight cruisers, and 15 destroyers. The disparity appeared crushing. Only in numbers of available aircraft and submarines was there near parity between the two sides. Despite various frictions developed in the execution, it appeared—barring something extraordinary—Yamamoto held all the cards.

Unfortunately for Yamamoto, something extraordinary had happened. The worst fear of any commander is for an enemy to learn his battle plan in advance, which was exactly what American cryptographers had done, thanks to breaking the Japanese naval code D (known to the U.S. as JN-25). As a result, Admiral Chester Nimitz, the Pacific Fleet commander, was able to circumvent both of Yamamoto's security measures and position his outnumbered forces in the exact position to conduct a devastating ambush. By Nimitz's calculation, his three available carrier decks, plus Midway, gave him rough parity with Nagumo's First Mobile Force.

Following a foolish nuisance raid by Japanese flying boats in May,[14] Nimitz dispatched a minesweeper to guard the intended refueling point for Operation K, causing the reconnaissance mission to be aborted and leaving Yamamoto ignorant of whether Pacific Fleet carriers were still at Pearl Harbor. (It remains unclear why Yamamoto permitted the early flight, when pre-attack reconnaissance was essential to the success of MI.) He also dispatched his carriers toward Midway early, and they passed the intended picket line force of submarines before they arrived on station, negating Yamamoto's back-up security measure. Nimitz's carriers then positioned themselves to ambush the First Mobile Force when it struck Midway. A token cruiser and destroyer force was dispatched toward the Aleutians, but otherwise ignored it. Days before Yamamoto expected American carriers to interfere in the Midway operation, they destroyed the fo