Key point: Tokyo's warplanners mistakenly thought that Washington would demoralized and sue for peace. However, they did not think through what a longer war would take to win.
Planning a war requires assumptions. However, there should be as few assumptions as possible, otherwise one can assume away all one’s problems. Japanese shortfalls in resources influenced their assumptions in planning for World War II. Because Japan could not successfully fight a long war, planners assumed it would be short—in accordance with the decisive battle doctrine. One big naval battle with the U.S. Pacific Fleet, early in the war, and Japan would emerge victorious.
The U.S., on the contrary, always assumed that a war with Japan would be a war of attrition. Because attrition would rule, U.S. planners assumed that a decisive battle, if one occurred, would be the outcome of years of attrition and would result in a U.S. victory. A naval blockade and air bombardment of the home islands would then force the Japanese to surrender.
Japan Was Blind to Its Own Weakness
The Japanese assumed away their enemy’s capabilities and underestimated their enemy’s quality, quantity, bravery, and strategic grasp, partly and no doubt subconsciously because Japan realized it could not defeat strong enemies. The most serious short-term strategic failure in estimating the enemy concerned the Allies’ ability to recuperate after the first Japanese blows. Concurrently, the Japanese woefully underestimated the length of time it would take the Allies to launch counteroffensives. The most serious long-term strategic failure was Japan’s complete inability to understand its own industrial weakness and the overwhelming industrial power of its enemies.
Japan had no guarantee or assurance that Germany would declare war on the United States. Japan began the war facing the possibility that every bit of U.S. manpower, matériel, and resolve (and a little of Britain’s) would be aimed at Japan alone. The Japanese did worry about this, but they assumed it away with the bland comment, “This must be watched…” Japan’s gamble is all the more hopeless in retrospect when one considers how quickly the Pacific War would have been won if the U.S. had not immediately prioritized, in concert with its Allies, the defeat of Germany.
Because Japan did not understand war, they could not accurately predict the ability of the U.S. to mobilize its resources. A competent general staff can address “known knowns” or “known unknowns” or even “unknown unknowns” and work toward learning what it does not know. The Japanese, however, blinkered their approach to war with a plethora of unknown unknowns.
As an example, they did not understand the breadth of the U.S. educational infrastructure and did not believe that the U.S. could train the officers, noncommissioned officers, and specialists needed to take back Japan’s conquests. Japan’s training techniques, such as naval aviator training, did not allow for the efficient transformation of the average Japanese aviator into a competent pilot. Therefore, the Americans, they believed, could not do it either. The Japanese had not adequately studied the American or British armies and therefore could not fathom their latent aviation airfield engineering capabilities.
Japan’s Poor Use of Intelligence
The Army and Navy assigned mediocre personnel to their limited number of intelligence slots and did not appreciate what intelligence and analysis could do. The Navy considered intelligence a secondary function. Although the collection of intelligence was good, its dissemination to tactical elements was poor. The Navy’s operations division often ignored or did not believe its own intelligence, especially when that intelligence threatened planners’ assumptions. The Navy’s gross underestimation of the U.S. Navy just before Midway was a contributing factor to its disastrous defeat there.
The Japanese Army entered World War II with just 20 officers and 20 enlisted men at its army general staff intelligence section, and their focus was on the Soviets. Another two or three officers addressed air intelligence. The Army war college gave only superficial intelligence training to its students, and neither the war college nor the air officers training school gave any special intelligence courses. A Japanese journalist recorded in 1943, “[We] are totally incapable of standing apart objectively and viewing positively the emotions and thought patterns of other countries. Accordingly, it is not possible for [us] to look at things objectively.”
Although Navy personnel had studied the American and British navies, the studies had always been on tactics. No one of note was interested in possible Western shipyard expansion, large-scale crew mobilization and training, or scientific exploration. Estimates, therefore, as to Western combat potentials, if explored, were fatally flawed or ignored. A strategic operation such as the early 1942 invasion of Burma, with an objective of cutting the Burma-to-China line of communications, failed to achieve its purpose when the West opened an airlift over the Himalayas. No Japanese planner could have dreamed of an aerial supply line of such magnitude in such difficult conditions. Thus, an unknown unknown became a factor in the outcome of the war.
Repeated Underestimating of the Enemy’s Strength
Faulty estimates of enemy strength originated during fighting in China. There were, in 1937, a total of 10 fairly well-trained Chinese divisions. The remaining 200 or so divisions and division equivalents could claim only unsatisfactory to non-existent training. Equipment was obsolete and poorly maintained, while ammunition was dear and hard to replace. The Japanese learned their warrior trade and exercised their logistics by fighting the Chinese, an army described by an American as a “… medieval mob.”
The Japanese Army became spoiled by easy access to military intelligence about the Chinese. The Army ignored its own counter-intelligence practices, from its peacetime organization through training and into combat. There seemed no need for an elaborate operational intelligence system because the Japanese easily obtained intelligence from the Chinese themselves. In China, Japanese officers developed disdain for their foes. It was often worse than disdain; it became a virulent, decades-long, government-driven indoctrination of contempt. The Chinese were little better than animals and insects. China could easily be subdued. In fact, as War Minister Hajime Sugiyama had assured the Emperor in 1937, Japan could crush China in a month.
The army underestimated Soviet prowess, firepower, and logistical sustainability before Nomonhan in 1939. Japanese logisticians had assumed that the Soviets could not launch a major offensive any farther than 200-250 kilometers from a major supply base. The Japanese were having great difficulties themselves in supplying their own forces at 220 kilometers from a major base. Therefore, they believed Soviets must be similarly hobbled. However, the Soviets launched their victorious campaign 600 kilometers from the nearest major supply base.
Underestimating the enemy continued in the Philippines where Japanese army officers estimated the strength of General Douglas MacArthur’s 1942 Bataan army at 25,000 men when there were actually 80,000 on the peninsula. They estimated British forces in Singapore at 30,000 when there were 85,000. They estimated the Midway garrison at 750 men and 60 aircraft when there were 3,027 men and 121 combat aircraft. They underestimated the effectiveness of the U.S. Navy itself. They underestimated the toughness of Australian and U.S. infantry in New Guinea. They underestimated the deadly effect terrain and weather would have on their own soldiers.
The Japanese completely missed the timing of the Guadalcanal landing. They considered it inconceivable that the landing was anything more than a reconnaissance. They estimated Marine strength on Guadalcanal at 2,000 when there were over 10,000 early in the campaign and later at 10,000 when there were 23,000 Americans on the island. The Japanese estimated that there were two or three infantry companies at Milne Bay on New Guinea, so they landed 1,500 men against 9,458 Australians and Americans. Japanese planners on Bougainville underestimated by half the American forces holding the Empress Augusta Bay perimeter. These miscalculations did not improve with time. They missed the timing and underestimated the strength of the August 1945 Soviet invasion of Manchuria.
Japan Counted Planes and Ships Correctly, but Overlooked the Intangibles
Because Japan had not delved deeply into the alchemy of strategic air power, no one could predict how Allied strategic air capabilities might affect Japanese plans. As a result, they underestimated its considerable impact, both on field forces and on logistics. A known known was the extent America’s 1941 aviation strength. The Japanese knew what it was. In 1941, a known unknown for the Japanese was certainly a realistic estimate of America’s projected aircraft production for 1942. The Japanese knew what they did not know. This is a warrior’s view of his enemy. It is an immediate question that can be solved.
And they solved it. Their estimates of U.S. naval air strength in 1941 and increases into July 1942 were excellent. Their estimates of U.S. aircraft production through the end of 1943 were almost exactly in line with actual production. Japanese estimates of U.S. warship production through December 1945 were close enough for any staff to plan a war. They did stumble badly on merchant tonnage, estimating U.S. construction capacity in 1943 at five million tons versus the actual 19.2 million tons.