World War II: Admiral Isoroku Yamamoto

The Architect of Pearl Harbor

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

Isoroku Yamamoto (April 4, 1884–April 18, 1943) was the commander of the Japanese Combined Fleet during World War II. It was Yamamoto who planned and executed the attack on Pearl Harbor in Hawaii. Initially against war, Yamamoto nevertheless planned and participated in many of the most important battles of the war. He was finally killed in action in the South Pacific in 1943.

Fast Facts: Isoroku Yamamoto

  • Known For: Isoroku Yamamoto was the commander of the Japanese Combined Fleet during World War II.
  • Also Known As: Isoroku Takana
  • Born: April 4, 1884 in Nagaoka, Niigata, Empire of Japan
  • Parents: Sadayoshi Teikichi, and his second wife Mineko
  • Died: April 18, 1943 in Buin, Bougainville, Solomon Islands, Territory of New Guinea
  • Education: Imperial Japanese Naval Academy
  • Awards and Honors:  Grand Cordon of the Order of the Chrysanthemum (posthumous appointment, Grand Cordon of the Order of the Rising Sun with Paulownia Flowers (April 1942), Grand Cordon of the Order of the Rising Sun (April 1940); the subject of many books and movies
  • Spouse: Reiko Mihashi
  • Children: Yoshimasa and Tadao (sons) and Sumiko and Masako (daughters)
  • Notable Quote: "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."

Early Life

Isoroku Takano was born April 4, 1884, in Nagaoka, Japan, and was the sixth son of samurai Sadayoshi Takano. His name, an older Japanese term for 56, referenced his father's age the time of his birth. In 1916, following the death of his parents, the 32-year-old Takano was adopted into the Yamamoto family and assumed its name. It was a common custom in Japan for families without sons to adopt one so that their name would continue. At age 16, Yamamoto entered the Imperial Japanese Naval Academy at Etajima. Graduating in 1904 and ranked seventh in his class, he was assigned to the cruiser Nisshin.

Early Military Career

While on board, Yamamoto fought in the decisive Battle of Tsushima (May 27-28, 1905). During the engagement, Nisshin served in the Japanese battle line and sustained several hits from Russian warships. In the course of the fighting, Yamamoto was wounded and lost two fingers on his left hand. This injury led to him earning the nickname "80 sen," as a manicure cost 10 sen per finger at the time. Recognized for his leadership skill, Yamamoto was sent to the Naval Staff College in 1913. Graduating two years later, he received a promotion to lieutenant commander. In 1918, Yamamoto married Reiko Mihashi with whom he would have four children. A year later, he departed for the United States and spent two years studying the oil industry at Harvard University.

Returning to Japan in 1923, he was promoted to captain and advocated for a strong fleet that would allow Japan to pursue a course of gunboat diplomacy if necessary. This approach was countered by the Army, which viewed the Navy as a force for transporting invasion troops. The following year, he changed his specialty from gunnery to naval aviation after taking flying lessons at Kasumigaura. Fascinated by air power, he soon became the school's director and began to produce elite pilots for the Navy. In 1926, Yamamoto returned to the United States for a two-year tour as the Japanese naval attaché in Washington.

Early 1930s

After returning home in 1928, Yamamoto briefly commanded the light cruiser Isuzu before becoming captain of the aircraft carrier Akagi. Promoted to rear admiral in 1930, he served as a special assistant to the Japanese delegation at the second London Naval Conference and was a key factor in raising the number of ships the Japanese were permitted to build under the London Naval Treaty. In the years after the conference, Yamamoto continued to advocate for naval aviation and led the First Carrier Division in 1933 and 1934. Due to his performance in 1930, he was sent to the third London Naval Conference in 1934. In late 1936, Yamamoto was made the vice minister of the Navy. From this position, he argued strenuously for naval aviation and fought against the construction of new battleships.

Road to War

Throughout his career, Yamamoto had opposed many of Japan's military adventures, such as the invasion of Manchuria in 1931 and the subsequent land war with China. In addition, he was vocal in his opposition to any war with the United States and delivered the official apology for the sinking of USS Panay in 1937. These stances, along with his advocating against the Tripartite Pact with German and Italy, made the admiral very unpopular with the pro-war factions in Japan, many of which put bounties on his head. During this period, the Army detailed military police to conduct surveillance on Yamamoto under the guise of providing protection from potential assassins. On August 30, 1939, Navy Minister Admiral Yonai Mitsumasa promoted Yamamoto to commander-in-chief of the Combined Fleet commenting, "It was the only way to save his life—send him off to sea."

Following the signing of the Tripartite Pact with Germany and Italy, Yamamoto warned Premier Fumimaro Konoe that if he were forced to fight the United States, he expected to have success for no more than six months to a year. After that time, nothing was guaranteed. With war almost unavoidable, Yamamoto began planning for the fight. Going against traditional Japanese naval strategy, he advocated a quick first strike to cripple the Americans followed by an offensive-minded "decisive" battle. Such an approach, he argued, would increase Japan's chances of victory and might make the Americans willing to negotiate peace. Promoted to admiral on November 15, 1940, Yamamoto anticipated losing his command with the ascension of General Hideki Tojo to prime minister in October 1941. Though old adversaries, Yamamoto retained his position due to his popularity in the fleet and connections to the imperial family.

Pearl Harbor

As diplomatic relations continued to break down, Yamamoto began planning his strike to destroy the US Pacific Fleet at Pearl Harbor, Hawaii, while also outlining plans for drives into the resource-rich Dutch East Indies and Malaya. Domestically, he continued to push for naval aviation and opposed the construction of the Yamato-class super-battleships, as he felt they were a waste of resources. With the Japanese government set on war, six of Yamamoto's carriers sailed for Hawaii on November 26, 1941. Approaching from the north they attacked on December 7, sinking four battleships and damaging an additional four—beginning World War II. While the attack was a political disaster for the Japanese due to the United States' desire for revenge, it provided Yamamoto with six months (as he anticipated) to consolidate and expand their territory in the Pacific without American interference.


Following the triumph at Pearl Harbor, Yamamoto's ships and planes proceeded to mop up Allied forces across the Pacific. Surprised by the speed of the Japanese victories, the Imperial General Staff (IGS) began to ponder competing plans for future operations. While Yamamoto argued in favor of seeking a decisive battle with the American fleet, the IGS preferred to move toward Burma. Following the Doolittle Raid on Tokyo in April 1942, Yamamoto was able to convince the Naval General Staff to let him move against Midway Island, 1,300 miles northwest of Hawaii.

Knowing that Midway was key to the defense of Hawaii, Yamamoto hoped to draw the American fleet out so that it could be destroyed. Moving east with a large force, including four carriers, while also sending a diversionary force to the Aleutians, Yamamoto was unaware that the Americans had broken his codes and were informed about the attack. After bombing the island, his carriers were struck by U.S. Navy aircraft flying from three carriers. The Americans, led by Rear Admirals Frank J. Fletcher and Raymond Spruance, managed to sink all four Japanese carriers (Akagi, Soryu, Kaga, and Hiryu) in exchange for the USS Yorktown (CV-5). The defeat at Midway blunted Japanese offensive operations and shifted the initiative to the Americans.

After Midway

Despite the heavy losses at Midway, Yamamoto sought to press forward with operations to take Samoa and Fiji. As a stepping stone for this move, Japanese forces landed on Guadalcanal in the Solomon Islands and commenced building an airfield. This was countered by American landings on the island in August 1942. Forced to fight for the island, Yamamoto was pulled into a battle of attrition that his fleet could not afford. Having lost face due to the defeat at Midway, Yamamoto was forced to assume the defensive posture preferred by the Naval General Staff.


Throughout the fall of 1942, he fought a pair of carrier battles (Eastern Solomons & Santa Cruz) as well as numerous surface engagements in support of the troops on Guadalcanal. Following the fall of Guadalcanal in February 1943, Yamamoto decided to make an inspection tour through the South Pacific to boost morale. Using radio intercepts, American forces were able to isolate the route of the admiral's plane. On the morning of April 18, 1943, American P-38 Lightning planes from the 339th Fighter Squadron ambushed Yamamoto's plane and its escorts near Bougainville. In the fight that ensued, Yamamoto's plane was hit and went down, killing all on board. The kill is generally credited to 1st LieutenantRex T. Barber. Yamamoto was succeeded as commander of the Combined Fleet by Admiral Mineichi Koga.

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Hickman, Kennedy. "World War II: Admiral Isoroku Yamamoto." ThoughtCo, Aug. 26, 2020, Hickman, Kennedy. (2020, August 26). World War II: Admiral Isoroku Yamamoto. Retrieved from Hickman, Kennedy. "World War II: Admiral Isoroku Yamamoto." ThoughtCo. (accessed March 30, 2023).