Yamamoto Isoroku


A longtime advocate for the power of aircraft carriers, Admiral Yamamoto Isoroku is best known for the planning of the Japanese attack at Pearl Harbor. His role in the policy side of that plan is much debated; some argue that he saw the danger, and crafted the plan with the greatest of reluctance, while others contend that he sincerely believed that it was possible to drive American naval power from the Pacific with a devastating blow, and that he pursued this strategy with relative autonomy. It is likely that the debate continues because there are elements of truth on both sides. Admiral Yamamoto was a farsighted planner who constructed a daring plan that almost succeeded, but the shortcomings in his plan proved fatal for himself and for the regime he served.

Isoroku was born in 1884 at Nagaoka. He was a junior son of a principal, but life brought him very different opportunities. He received the Yamamoto name through adoption; he prepared for a naval career through study in the academy at Etajima. He completed his studies in 1904, and war with Russia was looming. He served on the cruiser Nishin, fighting in the Battle of Tsushima. He was wounded, losing two fingers, but he had served in the Imperial Japanese Navy’s greatest victory, and indeed, one of the greatest naval victories ever. The IJN spent the remaining forty years of its existence endeavoring to preserve the advantages and match the achievements of Tsushima. In later years, Yamamoto would show clearer vision than most in recognizing that carriers had overtaken battleships in importance, but all the same, he would struggle in vain to win with them the kind of victory he had seen at the beginning of his career.

Even before World War I, Japan regarded the United States as a rival in the Pacific. Despite this distrust, the two nations were at least nominally allies during the last year and a half of the war. When the war had ended, Yamamoto attended Harvard to study English; naturally, this entailed learning a fair amount about the American culture and way of life. Two other subjects would also prove very important later: a detailed study of oil as a strategic resource, and the game of poker. Poker was more than a casual pastime for Yamamoto while he lived in Boston; the art of bluffing and the calculation involved in assessing the bluffs of one’s opponents resonated powerfully with him.

Two years later, he resumed his active naval service, and in 1924 he was given a key post at an air station, where he became familiar with the capabilities of air power. 1926 brought another two years of work in the United States, this time serving as naval attache in the capital. This visit engendered in him a low estimation of America’s peacetime navy. Indeed, his gamble in 1941 might be seen as an effort to defeat the U.S. Navy before the full weight of wartime mobilization could transform the battle into a duel with America’s economic might. Yamamoto knew that the latter was a fight that Japan could not win.

His time in Washington was followed by two years in command of the Akagi, one of Japan’s first aircraft carriers. The experience contributed to his growing estimation of the power of naval aviation, in contrast to the majority of his colleagues, who saw the battleship as the apex of naval power. Yamamoto would later compare battleships to samurai swords with regard to their military significance in modern warfare. His star rose in the early 1930s, playing an important role in the diplomatic work that scrapped old restrictions on the size of Japan’s navy, overseeing Japan’s carrier force, and in 1935, becoming the navy’s vice-minister.

Here he served until 1939. It was a period that embroiled him in controversy, however. If his ideas on carriers and battleships were unorthodox, it was his views on Japan’s prospects in a future war that were deeply unpopular. The Japanese Army’s adventures in China raised serious tensions with other major powers, especially the United States and Britain. Many thought that the time had come to deal decisively with these rivals, and secure Japan’s dominance in the Pacific (and access to valuable resources). Yamamoto’s familiarity with the United States persuaded him that such an effort was foolish. In the event of such a war, Yamamoto predicted up to a year of success, followed by certain failure. As Japan began to align itself with Germany and Italy, Yamamoto opposed this as well, seeing it as a step that guaranteed the kind of war Japan could not win. Japan’s nationalists were furious with him, and at least one attempt on his life was planned.

As much to save Yamamoto’s life as for any other reason, the minister of the navy placed him in charge of Japan’s Combined Fleet. The exact constitution of this entity was never formalized, but it effectively gave him command of most of Japan’s naval forces. Yamamoto remained at this post until his death; it also gave him the final responsibility for planning the war he had never wanted to see. It was a responsibility that tapped into his instincts as a poker player. Fighting the United States was a gamble that threatened total defeat; if he could not withdraw from that game, then he could win only through a colossal bluff. In any long war, the United States would crush Japan, so his only hope lay in persuading the United States to give up before it became a long war.

His hope was to present America with a series of threats that, together, would be overwhelming. The logic of diplomatic activities in the previous three years suggested that the United States would face war with Japan, Germany and Italy more or less simultaneously. If the American Pacific Fleet could be destroyed in a massive blow, the United States would be faced with a strong enemy and no immediate means to defeat him. If the destruction of the fleet could be coupled with rapid expansion throughout the western Pacific and in southeast Asia, the scope of the problem would be so overwhelming that the United States would have to conclude peace.

The movement of the Pacific Fleet from San Diego, California to Pearl Harbor offered Yamamoto the opportunity to attempt such a gamble. Even at this juncture, Yamamoto argued that the only choices were a risky plan like the Pearl Harbor attack, or a diplomatic accommodation with the United States. Unlike many, who believed that such an attack could be won only the loss of several Japanese vessels, Yamamoto was convinced that carrier-borne aircraft could prevail with minimal casualties. It was the aftermath that concerned him. It was essential that the losses in the American Pacific Fleet were nearly total; it could not be possible to maintain organized resistance with the remainder, or America would fight on. Also, the attack depended on secrecy, and that required very careful timing. It was decided that the declaration of war would be delivered just a half hour before the planes arrived at Pearl Harbor; they would take off while Japan was still nominally at peace. Yamamoto’s familiarity with American culture made him one of the voices of caution with regard to this stratagem: any error in timing that resulted in an attack coming before a formal declaration of war would fatally undermine the plan. The attack might proceed with optimal effect, but the opportunity to end the war diplomatically would be lost irretrievably.

Yamamoto’s concerns were noted and set aside; the proposed attack was authorized, and from that point, it was entirely in Yamamoto’s hands. Luck failed him on two counts: the American carriers were not in port when the attack was launched, ensuring that the most valuable naval assets in the coming war would not be touched, and the declaration of war was delivered too late. Together, these factors were devastating for Yamamoto’s strategy, but either one independently would have been enough to defeat his plan. As effective as it seemed at the time, Pearl Harbor was doubly a failure.

For his part, Yamamoto was well aware of the significance of these factors. It remains uncertain whether he really made his famous comment about awakening “a sleeping giant,” but certainly, he understood the prospect. A month later, he disavowed any pride in his achievement, saying, “A military man can scarcely pride himself on having ‘smitten a sleeping enemy’; in fact, to have it pointed out is more a matter of shame.” Still, it fell to him to oversee the follow-through on his plan, and the speed of Japanese expansion in the Pacific in the immediate wake of Pearl Harbor is impressive. Yamamoto was eager for an opportunity to draw out the Pacific Fleet, hoping to salvage some of his strategic goals by definitively defeating the U.S. Navy in a second engagement. His military superiors felt that this effort was too risky.

In the end, Yamamoto got his way as a result of the Doolittle Raid. This attack on the Japanese Home Islands compelled Japan’s military leaders to countenance an effort to destroy the Pacific Fleet, regardless of how risky it might be. Still, their initial hesitation was as valid as Yamamoto’s reluctance to fight the United States in the first place; Yamamoto’s fleet became the hunted instead of the hunter, and the Americans won an important victory at Midway.

After Midway, Yamamoto’s last ten months were characterized by resignation in the face of encroaching defeat. The Americans had seized the initiative, and Yamamoto was compelled to accept a defensive role. Significantly, however, he sought to cling to Japan’s island outposts, using up men and material that might have served more effectively in a mobile form of defense. He made American gains as costly as possible, and thereby served the expectations of Japanese honor, but he also hastened Japan’s eventual defeat.

Yamamoto was not to see that day, however. Alerted by a decoded radio message, American P-38 fighters shot down the G4M “Betty” bomber carrying Yamamoto to Japanese bases in the Solomon Islands on April 18, 1943. Yamamoto’s plane crashed into the ocean near Bougainville.

In many respects, Yamamoto had been among the most realistic Japanese military leaders during World War II. He saw the folly of engaging the United States in battle, but was constrained by official policy to execute just such a plan. At the same time, he was at heart an inveterate gambler. His only hope for victory had lain in a high-risk strategy. That strategy had failed, making even a substantial victory a pyrrhic one in the final analysis. Like many gamblers, he responded to a losing streak with another risky move that could make good prior losses, or drive him even more deeply into debt. After Pearl Harbor, Japanese defeat was nearly certain; after Midway, it became only a matter of time.



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Cowley, Robert et al.  The Reader’s Companion to Military History.  Houghton Mifflin Harcourt, 2001

Dear, I.C.B.  The Oxford Guide to World War II. Oxford, 1995

Parrish, Thomas.  Simon and Schuster Encyclopedia of World War II.  Simon and Schuster, 1978


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