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Pearl Harbor: Preparations for War

In late 1941, a Japanese weapon honed in battle was about to be turned upon the U.S. Pacific Fleet

Operation Z

Once Yamamoto’s bold plan for a sudden attack won approval, it became “Operation Hawaii,” also called “Operation Z,” and forged rapidly ahead under the admiral’s oversight.

By then, wooden fairings had been developed for the Japanese torpedoes, hindering the tendency to go deep before beginning their run-in near the surface. In one mock torpedo-bombing exercise after another, Japanese air crews demonstrated that the problem of using torpedoes in shallow water had been solved.

In October 1941, while Stark was being misinformed about Kimmel’s access to Magic intercepts, Japanese airmen intensified training for Pearl Harbor in the beautiful, westerly city of Kagoshima. By then, wooden fairings had been developed for the Japanese torpedoes, hindering the tendency to go deep before beginning their run-in near the surface. In one mock torpedo-bombing exercise after another, Japanese air crews demonstrated that the problem of using torpedoes in shallow water had been solved.

Adm. Chuichi Nagumo

Adm. Chuichi Nagumo, whose caution left Pearl Harbor’s submarine base, ship repair facilities, and tank farm intact, and who six months later would lose his carriers at the Battle of Midway. National Archives photo

In Washington, Japan’s Ambassador Kichisaburo Nomura continued to negotiate vigorously, reflecting his nation’s ongoing search for an outcome that would avoid war and win U.S. acquiescence to Japanese hegemony in Asia. Though military men ruled the Japanese Empire with the Emperor in some respects a symbolic leader, there is no question that top leaders, including Minister of War Gen. Hideki Tojo, wanted to avoid a fight with Americans. To bolster their negotiations for a settlement, they sent a second diplomat, Saburo Kurusu, to Washington. Nomura and Kurusu became a familiar duo, seeking appointments with Secretary of State Cordell Hull and others. They never learned that Hull was even more a figurehead than their own emperor (the State Department was essentially being run by deputy Sumner Welles), and they never knew that Roosevelt, Hull, and Welles knew their negotiation positions in advance, thanks to the Magic intercepts.

On Oct. 23, 1941, in Kagoshima, Vice Adm. Chuichi Nagumo, who would command the carrier strike force, and Cmdr. Mitsuo Fuchida, who would command the striking force’s planes, received a briefing. Nagumo was a curious choice to assemble history’s first aircraft carrier task force – a 54-year-old man of “underlying anxiety,” in the words of one observer, “chosen solely on the basis of seniority, skilled in surface warfare but without experience in aviation. He appears to have had cursory interest in the briefing.”

The name of that battle was on everyone’s lips: Taranto.

Fuchida, on the other hand, was enraptured. The briefer was Lt. Cmdr. Takeshi Naito, Japan’s naval attaché in Berlin, who had flown to Italy to observe the aftermath of an unprecedented British torpedo raid. The name of that battle was on everyone’s lips: Taranto.

Also of great interest to American planners, including Stark and Kimmel, the battle had taken place a year earlier, on November 10, 1940, when just one British carrier, HMS Illustrious, sent a mere 21 fabric-covered, open-cockpit Fairey Swordfish biplane torpedo bombers to attack Mussolini’s battle fleet, nestled safely in its home port at Taranto, Italy. The Italian warships were protected by anti-aircraft guns and a sophisticated early-warning system that lacked radar but used powerful acoustic warning devices. Unlike U.S. warships at Pearl Harbor, the Italian vessels also were shielded by anti-torpedo nets slung across the harbor.

Fairey Swordfish

The Royal Navy carrier HMS Illustrious, in company with battleship HMS Warspite, launches Fairey Swordfish biplane torpedo bombers. The Taranto raid, flown by a mere 21 Swordfish launched from Illustrious, achieved great results and was eagerly studied by the Japanese. Imperial War Museum photo

The Swordfish struck in two waves an hour apart. The first, led by Lt. Cmdr. Kenneth Williamson, consisted of six torpedo-armed Swordfish, plus six carrying flares or bombs. The Swordfish carried a crew of two that night, a pilot and an observer, the usual gunner left behind in favor of a large auxiliary fuel tank next to the observer. The first wave flew into bitter cold and thick clouds, flying on instruments, then after about 30 minutes in the air, reached a clear sky lit by a crescent moon. Six battleships, seven cruisers, and 28 destroyers lay in their moorings at Taranto. They boasted 600 anti-aircraft guns. Yet the first wave lost just one Swordfish, hitting two battleships and Taranto’s seaplane base.

The second wave of nine Swordfish, led by Lt. Cmdr. Ginger Hale, had an unlucky start, losing two planes to mechanical glitches. With his remaining seven Swordfish, Hale flew into Taranto through heavy anti-aircraft fire. Flare-carrying planes went in first and lit up the target. The action that followed was one-sided. The British lost two men killed and two taken prisoner. The Italians lost 40 men, and, more importantly, lost a symbol; Taranto, the Italian Navy’s main naval bastion, had been shown to be vulnerable. The British disabled three battleships and four other warships, and shifted the balance of power in the Mediterranean. When ex-naval attaché Naito gave details to air wing commander Fuchida in October 1941, Fuchida asked questions again and again; their conversation dragged into the night.

In the snow and fog of Tankan Bay in the Kurile Islands, Nagumo’s First Air Fleet (1st Koku-Kantai) sailed on the morning of Nov. 26, 1941, to follow a leisurely course along the 43-degree North parallel far from cluttered sea lanes. The unheralded departure of the First Air Fleet happened only hours before a message to Kimmel warned of impending Japanese action – but made no mention of the Hawaiian Islands. “This dispatch is to be considered a war warning,” began the message. Japan might launch “an amphibious expedition against either the Philippines, Thai or Kra Peninsula, or possibly Borneo.”

Kimmel and Army commander Lt. Gen. Walter C. Short had received numerous other cables from Washington suggesting that Japanese action might be coming soon, but they are given less credence in historical accounts because they lacked the crucial two words “war warning,” included more or less as an afterthought.

Kimmel and Army commander Lt. Gen. Walter C. Short had received numerous other cables from Washington suggesting that Japanese action might be coming soon, but they are given less credence in historical accounts because they lacked the crucial two words “war warning,” included more or less as an afterthought. It did not help that Kimmel and Short were poorly informed about U.S. code-breaking efforts. The November 27 message is often given great weight because it begins with the words “war warning.” But numerous similar messages had been sent without those two crucial words. Rear Adm. Richmond K. Turner, who drafted the message, later told historian Gordon Prange that he meant “war warning” to “express the strong conviction on the part of the [Navy] Department that war was surely coming.” None suggested that Japan might strike Pearl Harbor.

Mitsubishi A6M2 "Zero"

A Japanese Navy Mitsubishi A6M2 “Zero” fighter (tail code A1-108) takes off from the aircraft carrier Akagi on its way to attack Pearl Harbor on Dec. 7, 1941. U.S. Naval History and Heritage Command photo

While the fleet proceeded – contrary to myth, it crossed the North Pacific without being seen or detected by anyone – messages from Tokyo to the Japanese embassy in Washington gave negotiators Nomura and Kurusu a position to take to Hull, plus a fallback position. Thanks to Magic, Hull was aware of both when the Japanese diplomats showed up.

No one in the room knew that the first aircraft carrier strike force ever assembled was proceeding toward its target, but U.S. leaders knew the Japanese were no longer prepared to accept any agreement that would also be acceptable in Washington. On Dec. 1, 1941, the First Air Fleet received the coded “go” signal from Tokyo (“Niitakayama Nobore,” or “Climb Mount Niitaka,” the Japanese name for the highest mountain on Formosa) even though negotiations between the U.S. and Japanese governments were still taking place. The fleet refueled on December 3, now drawing close to its destination. In Washington, two sets of code experts began decoding 13 parts of a 14-part message from Tokyo to Nomura, which the ambassador was to deliver to the Americans at 1:00 p.m. Washington time (7:00 a.m. Hawaii time) on Sunday, December 7. At the Japanese embassy, the task of decoding was given to an employee in whom there was impeccable trust, but whose typing skills were poor. The U.S. codebreakers of the Magic program had no such problem. It would turn out, in the end, that Nomura and Kurusu would be ushered in to see Hull one hour and 43 minutes later than they planned and 53 minutes after the attack began. Nomura and Kurusu never knew about the First Air Fleet, and only learned about the attack after their awkward meeting with Hull, who learned about it while they waited to see him. Those events came later. At 3:00 a.m. on December 7, (Hawaii time, the date on the western side of the international dateline), the First Air Fleet had reached its fly-off position.

At 5:45 a.m., the first A6M2 combat air patrol lifted from carrier decks. At 6:00 a.m., Comdr. Mitsuo Fuchida took off at the head of 189 aircraft. At 7:15 a.m., Lt. Cmdr. Shigekazu Shimazaki launched with 170 aircraft. The sun came up at 6:43 a.m., silhouetting the fighters and bombers high over the ocean as they flew toward Oahu.

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Robert F. Dorr is an author, U.S. Air Force veteran, and retired American diplomat who...

    li class="comment byuser comment-author-dwight-jon-zimmerman even thread-even depth-1" id="comment-18329">
    Dwight Jon Zimmerman
    Dwight Jon Zimmerman

    Another fine article, Bob. Enjoyed it immensely.