Yamamoto Isoroku was described by his Japanese biographer as “short, plump, superstitious, a womanizer and a passionate gambler. And, in his time, he shook the world” (Agawa 1979: endcover). Yamamoto, the most renowned commander the Imperial Japanese Navy (IJN) produced during World War II, made such an impact on naval operations in the Pacific that President Franklin D. Roosevelt personally ordered the US Navy to “get Yamamoto” — it did, deliberately ambushing his aircraft on April 18, 1943, in the longest-range fighter intercept mission of the war.
Yamamoto was a link between an old and new Japan. He was born Takano Isoroku in 1884, into a minor samurai family. His father fought with the shogunate forces in the civil wars; the Meiji state marginalized him in retaliation. This led his son to come under the influence of US missionaries during his early education. This produced a lasting interest in all things western and a good command of the English language. In due course Japan's need to reconcile old and new allowed the young man to enter the Naval Academy, graduating in 1904. He fought in the Russo-Japanese War. In 1916 he took the Yamamoto name when he was adopted by that family, to continue the name of a more notable house with no male heir. Identified as a rising star, Yamamoto was sent to the United States in 1919 to learn more about the country. Two years of study at Harvard, extensive trips around the country, plus a long tour of the West in 1922, and a stint as naval attaché in Washington from 1925 to 1928, rounded off this combination of old and new. Yamamoto developed healthy respect for western industrial strength and modern technology, great interest in the possibilities of naval aviation in the vast reaches of the Pacific, and determination to strengthen the navy as a modern service.
This background placed Yamamoto in an awkward position in the debate that dominated the IJN between the world wars: whether to abide by the treaties agreed at Washington in 1922 and try to cooperate with the western powers, or reject restrictions that imposed inequality on the IJN and pursue an imperial policy that would increase Japanese influence in Asia at western expense. Yamamoto consistently argued against provoking the West, but hardliners gained the ascendancy. His entrapment in politics was, however, offset by his work to develop naval aviation, in which he played a leading role in a variety of posts. This included learning to fly at the age of 40. Yamamoto did much to develop the aircraft and equipment that by the late 1930s gave the IJN more potent naval aviation than its western rivals. He also played a leading role in devising concepts and doctrine by which it could be used effectively, including organizing the air division for both land-based and carrier strike forces. His most important innovation was the idea to concentrate fleet carriers in powerful combined strike forces as the main offensive power of the fleet, superseding both the older focus on the battleship and earlier ideas about using carriers individually.
Yamamoto served as navy vice minister from 1936 to 1939 and tried to prevent Japan's alignment with the Axis Powers. But the tide of politics ran the other way, and only his leading role in modernizing the fleet kept hardliners from moving against him. His allies had him appointed commanderin-chief of the Combined Fleet, the main striking force, to keep him safely at sea. Yamamoto opposed going to war with the Americans, but also prepared the fleet to defeat the US Navy (USN) should war come nonetheless. Yamamoto was not the only senior Japanese officer to understand the danger of waging war against the Americans, but he did make the celebrated statement that if ordered to attack he could run wild in the Pacific for the first six months — but after that the country would have to fight for its very survival (Hoyt 1993: 103). Yamamoto concluded that the only slender hope Japan had to survive a war with the Americans was to quickly destroy the USN main fleet in a decisive battle. This would force the Americans to rebuild their naval power while Japan dug in, perhaps strongly enough to wear down the US counteroffensive and provoke a peace settlement through war weariness. To accomplish this he insisted on concentrating the IJN's striking power to launch a surprise attack on the US Pacific Fleet at Pearl Harbor in Hawaii, an operation approved only after he twice threatened to resign.
Yamamoto realized how dangerous it was to provoke US public opinion by surprise attack, and understood how important it was to destroy the Pacific Fleet's aircraft carriers and base installations. He planned and oversaw the notorious attack on December 7, 1941, that began the Pacific War, but could not prevent either failure to declare war first or failure to destroy the crucial targets. Yamamoto understood that Japan now faced an aroused enemy determined to destroy Japanese power. He decided to bring the Pacific Fleet to a decisive engagement before it became too strong to fight. This led to the defeats at the Coral Sea in May and Midway in June 1942, which destroyed the carrier strike force he had so patiently developed. That forced Yamamoto to fight on increasingly bad terms. Accepting battle in the southwest Pacific, he tried to grind down US air and naval power in the Solomons, to keep the US advance at bay. During this campaign the Americans ambushed and killed him.
Yamamoto's fleet fought with the skill, discipline, and superior weapons he did so much to develop. But his tendency to adopt overly elaborate plans, plus his determination to smash the USN in a fleet action, made his fleet vulnerable. Yamamoto and his fleet were undone by one thing he saw coming plus another he never realized. Both came from the same source: modern US industrial capability. Yamamoto realized his enemy would only become larger and better equipped as the war dragged on. In his desperation to preempt this he did not realize his operations were heavily compromised by US signals intelligence, which systematically intercepted and decoded IJN message traffic. This played a crucial role in allowing the then-outnumbered Pacific Fleet to shatter Yamamoto's force at Midway — and enabled the Americans to track, trap, and kill Yamamoto himself. Yamamoto's death plunged Japan into a crisis of morale, sparked a change in grand strategy, and marked the highest tribute an enemy could pay to a naval commander. Yamamoto's life, character, and career reflected the nature and energy of the modern Japanese empire and its navy. But it also reflected the divisions neither could resolve, and the mismatch between ambitions and limitations that destroyed both.
SEE ALSO: Roosevelt, Franklin D. (1882–1945); Russo-Japanese War (1904–1905); Samurai; Washington Naval Conference (1921–1922); World War II: War in Asia.
I fear we have only awakened a sleeping giant, and his reaction will be terrible. Said after the Japanese attack on Pearl...
Japanese naval officer. Educated at the Japanese Naval Academy, Etajima, he was wounded in the Battle of Tsushima in the Russo-Japanese War ...
—Isoroku Yamamoto, Japanese admiral who conceived the Pearl Harbor attack We have awakened a sleeping giant and instilled in him a terrible resolve