Pearl Harbor never dies, and no living person has seen the end of it.[1]

In the spirit of a remorseless US Navy-style "hot wash," Alan D. Zimm, a Navy veteran and operations research specialist at the Johns Hopkins Advanced Physics Laboratory, delivers an end-to-end, down in the weeds critique of the Japanese attack on Pearl Harbor that belongs on the bookshelf of every student of the Pacific War. Make no mistake, it does not supplant Gordon W. Prange's epic history, At Dawn We Slept, after thirty years still the definitive account of Pearl Harbor from the perspective of the senior military and diplomatic figures involved. But Zimm offers far more detailed technical and tactical analysis as well as a much-needed corrective in matters where Prange[2] goes astray. Prange and his assistants became particularly close to Cdr. Mitsuo Fuchida,[3] the famed Japanese naval aviator who led the Pearl Harbor attack. Fuchida merits close attention because he originated some key misinformation about the attack that Prange perpetuates and Zimm convincingly refutes.

Attack on Pearl Harbor is another entry in a list of superb recent works of military history about the Pacific War, rich in operational and tactical detail, best exemplified in the work of John Lundstrom,[4] Jon Parshall and Anthony Tully,[5] and Richard B. Frank.[6] The principal myth Zimm seeks to refute by his detailed, unsparing analysis is Gordon Prange's characterization of Pearl Harbor as "one of the most daring and brilliant naval operations of all time." He amply demonstrates that the First Air Fleet, the carrier striking force of the Imperial Japanese Navy (IJN), did not in fact plan particularly well or engage in effective, realistic preparatory training. The success of the attack resulted more from the ineptitude and complacency of the US forces on Oahu than from the skill of Japanese aircrews. In a stark departure from Prange and nearly every other historian of Pearl Harbor, Zimm cuts this "victory" down to size.

No serious historian can deny that the Japanese attack on Pearl Harbor was a colossal strategic error, provoking a war with the United States that was hopeless from the outset. Zimm summarizes the lengthier argument by Prange that most senior IJN officers—including Adm. Isoroku Yamamoto, commander in chief of the Combined Fleet—knew that a prolonged war with the United States could not be won. The Navy leadership, however, was marginalized within the Army-dominated Japanese government. The IJN was obliged to confront the US Navy primarily to facilitate and protect the Japanese Army's war of conquest to the south, into Malaya and the East Indies. The Philippine Islands, lying so close on the flank of this gigantic operation, would have to be occupied as well. This in turn would certainly bring the United States into the war. Both Japanese and American war planners expected the US fleet to move west to relieve pressure on the Philippines and force a make-or-break confrontation with the Japanese Navy. Such a "decisive battle" had long been the central article of faith in Japanese naval strategy. Anticipating an early American advance into the central Pacific, the Japanese planned to decimate the US fleet as it moved west—by carrier airstrikes, submarine attacks, and cruiser and destroyer torpedo strikes—to the point where a depleted, exhausted American force could not win a showdown battle with the Japanese fleet. But the elephant in the room was the possibility that the United States might delay offensive operations in the Pacific while accumulating overwhelming naval strength through its superior industrial production. "Japan had little chance for victory in a long war, and the Japanese knew it. They adopted a short war strategy which offered a chance to win, and built their force, trained their men and developed their tactics to support this strategy. They had no solution to the 'long war' scenario—so they ignored it" (36).

When Admiral Yamamoto was ousted as Deputy Minister of the Navy (over his opposition to Japan's joining the Axis Pact), he assumed command of the Combined Fleet and quickly rejected the "decisive battle" concept in favor of a preemptive strike against the US fleet. His Pearl Harbor attack plan was brought to maturity by Cdr. Minoru Genda of the First Air Fleet staff—another figure Prange endows with heroic stature. Underlying this plan was Yamamoto's conviction that Japan's only hope was to destroy several battleships in the US Pacific Fleet, preventing any rapid advance into the central Pacific and so demoralizing the Americans as to induce peace negotiations.

Why the battleships? For all the signs and suppositions regarding Yamamoto's progressive attitude toward naval aviation—indeed, he had commanded both an aircraft carrier and a carrier division earlier in his career—evidence cited by both Prange and Zimm proves that he remained at heart a "battleship admiral": "Yamamoto was after battleships, mainly to strike a psychological blow against the United States, hoping that it would result in a negotiated peace after the Japanese had secured their conquests…. Yamamoto (and the rest of the Japanese command structure) was expecting to sacrifice at least two fleet carriers to this goal and perhaps more, making it a 'carriers for battleships' swap" (372).

Since, in 1941, the dominance of the aircraft carrier had yet to be demonstrated, Yamamoto reasoned that sinking several battleships would temporarily cripple the US Navy. Specifically, he reckoned that destroying four battleships would constitute a successful operation, and this he in fact achieved.

Zimm is a forceful and convincing myth-buster. He has changed my mind about one important tenet of received wisdom—that the Japanese should have mounted a second attack, targeting the port facilities and oil storage tanks at Pearl Harbor. Admirals Nimitz and Kimmel and the Navy's official historian, Samuel Eliot Morison, believed such an action would have seriously impaired the US Navy's operations in the South Pacific during the first year of the war. But Zimm persuasively shows that such an attack would have achieved only transitory results. Moreover, the First Air Fleet lacked adequate munitions to inflict serious damage on the Pearl Harbor infrastructure, a target set that had never figured seriously in Japanese planning. In any case, the US Navy had the resources and expertise to quickly repair any damage the Japanese might have inflicted. The myth persists that Fuchida and Genda argued strongly for a second attack, only to be rebuffed by an overly-cautious Admiral Nagumo, the First Air Fleet's commander. Fuchida's deceptive postwar testimony on this point is enshrined in both Prange's book and the movie Tora! Tora! Tora![7] (for which Fuchida was a technical advisor). Zimm establishes that no such disagreement ever took place and no second attack was ever seriously considered.

Zimm also seeks to dispel the myth that the famous "fourteen-part message" sent to Japan's ambassador in Washington, Admiral Nomura, constituted a declaration of war that Admiral Yamamoto and the Japanese leadership hoped to deliver precisely at 7:30 a.m. Hawaii time, about thirty minutes before the Pearl Harbor attack was to commence. This would ostensibly have made Japan not guilty of initiating hostilities before declaring war. However, no reasonable parsing of the message text yields language declaring war; certainly American leaders from President Roosevelt on down did not see it that way, as Prange and other historians have noted. But, unlike Zimm, Prange does point out that, early on December 7th, Tokyo sent Nomura a subsequent, very short message requesting that he deliver the fourteen-part message to the US Secretary of State by 1:00 p.m. Eastern Standard Time, that is, 7:30 a.m. in Hawaii. The Americans swiftly decoded this message, which struck some in Washington as an advance warning of war. Col. Rufus Bratton, a senior Army intelligence officer who had long believed Japan would launch a surprise attack at Pearl Harbor, promptly alerted Army Chief of Staff Gen. George C. Marshall, who dispatched a warning telegram to Lt. Gen. Walter C. Short in Hawaii. (This message was famously delayed, routed via commercial channels and arriving after the bombs had fallen.)

Why was the Pearl Harbor attack so successful, at least in Japanese eyes? As Zimm carefully documents, Minoru Genda's tactical planning was flawed and his counterpart Fuchida's execution was clumsy in many respects. Japanese aircraft lacked adequate radios, and Fuchida used flares to indicate whether surprise had been achieved. He bungled that all-important task, causing some confusion within the attack force. Yet, the First Air Fleet managed to put a large, reasonably well-trained strike force over Oahu and Pearl Harbor—a target-rich environment—with no immediate opposition. The Americans were completely surprised despite abundant strategic and tactical warning right up to the early hours of December 7th. Japanese midget submarines were detected and engaged while attempting to enter Pearl Harbor in the last hours of darkness, and a Japanese reconnaissance floatplane overflew the harbor about an hour before the strike force arrived. This aircraft and the strike force itself were detected by radar well over a hundred miles north of Hawaii. These events constituted "actionable intelligence" that should have given the Pacific Fleet and the Army forces on Oahu time to go to General Quarters, activate formidable antiaircraft defenses, launch fighter interceptors, and get some of the ships out of the harbor. Instead, reasons were found to exercise caution and avoid passing warnings up the chain of command. Zimm joins a chorus of historians who find this both shocking and inexcusable. He shows that about forty minutes of advance notice, properly used, would have both saved a number of battleships and increased Japanese aircraft losses—to the point of making the raid a complete failure.

Zimm thoroughly explicates the technical details of the raid, to include information about weapons, Japanese pre-strike training profiles and exercises, and each side's war gaming results both at the time and after the fact. His many charts and tables will satisfy the most discriminating scholars and modelers. Some interesting facts emerge: the IJN was certainly forward-looking in terms of carrier aviation, having commissioned no fewer than ten carriers by the end of 1941 and consolidating the six largest in the world's first carrier striking force—an unprecedented and farsighted operational decision for which Admiral Yamamoto deserves some (but not all) of the credit. The ten carriers mounted a total of about 550 aircraft, but the IJN began the war with barely six hundred carrier-qualified pilots and its too-exacting training program produced few replacements. Attrition was heavy even in the early months of victory—losses at Pearl Harbor alone amounted to 8 percent of those engaged. By the Midway campaign, six months later, the four participating Japanese aircraft carriers fielded about the same number of pilots and aircraft as the three USN carriers they encountered. Zimm also painstakingly details IJN munitions, including characteristics of the bombs, many of which were faulty or misused and directed against the wrong targets; the torpedoes, which had been modified for shallow-water use only just in time for the operation, though they were true "ship killers," were often wasted on minor targets.

Zimm's conclusions will remain definitive for the foreseeable future. The attack on Pearl Harbor was a fortuitous tactical success on its own deeply-flawed terms. (Appendix D, "The Perfect Attack," shows just how much more successful it might have been.) Zimm's profiles of major participants are spot on: Admiral Yamamoto, a figure of immense personal prestige within the Japanese Navy (and subsequently in the American imagination), was less a naval genius than a reckless and irresponsible gambler deluded about what the Pearl Harbor operation might accomplish.[8] Commander Genda was at best an operational planner of modest competence: the final attack plan was simple but too rigid, with small allowance for variables. Commander Fuchida was a strike leader of marginal ability who made critical errors during the attack and later inflated his achievements. On the other hand, Admiral Nagumo, commanding the First Air Fleet, was the prudent executor of a plan he had wisely opposed, not the timorous figure depicted by historians. On the American side, both Admiral Kimmel and General Short deserve the harsh verdict most historians have levied upon them. During the late fall of 1941—until a week prior to the attack—the military forces in Hawaii had maintained a high state of readiness. Had this been continued and the warning signs early on December 7th acted on promptly, the Japanese strike formations would have encountered a fleet at General Quarters, a profusion of antiaircraft guns at the ready, and more than eighty modern fighter planes in the air over Oahu, outnumbering the first-wave Japanese fighters two-to-one. Many more Japanese aircraft would have been downed and many fewer American ships sunk.

So, by all means, reread Gordon Prange's At Dawn We Slept, but definitely read Alan Zimm's Attack on Pearl Harbor for a fuller and more up-to-date understanding of an event that changed history and continues to fascinate.