Operation Storm: Japan's Top Secret Submarines and Its Plan to Change the Course of World War II (5 page)

In spite of his diplomatic experience, Yamamoto disliked obfuscation, which was one reason Americans warmed to him. In addition to being a maverick, he also had a tough streak. (You didn’t get to be CINC of the
Rengo Kantai
without one.) He also had a surprisingly mischievous side.
⁸
It wasn’t unusual for the commander in chief to do a headstand at a party, as an ice-breaking trick.
⁹
Though he didn’t drink (he’d learned as an ensign that he couldn’t handle alcohol),
¹⁰
he had a sweet tooth
¹¹
and a penchant for geisha houses. He also wrote mediocre poetry.
¹²
None of this was unusual for an Imperial Japanese naval officer, except perhaps his inability to drink. Etajima, Japan’s naval academy, prided itself on turning out renaissance men, and Yamamoto was no exception.

Standing five feet three inches, Yamamoto was shorter than the average Japanese.
¹³
He had a prominent nose, a strong chin peppered with scars, and a shaved head. Besides his surprisingly thick lips, his only distinguishing feature was two missing fingers on his left hand. He’d lost them during the 1905 Russo-Japanese War, when the barrel of an overheated deck gun exploded. Yamamoto had been serving aboard the
Nisshin
when the accident happened, and his body bore its scars for the rest of his life. One story has it that geishas teasingly nicknamed him “eighty
sen
”—two fingers, or
20
sen
less than the 100
sen
cost of a manicure.
¹⁴
He accepted the name with characteristic good humor.

What Yamamoto enjoyed most of all was gambling. Whether it was
shogi
, go, mah-jongg, billiards, roulette, or bridge, Yamamoto lived for games of chance.
¹⁵
As an accomplished gambler, he was willing to take a risk so long as the odds were calculable. Pearl Harbor had been a risk, and he’d won. Now he was looking to make his next big bet—which was why he’d gathered his senior officers.

Though Yamamoto could be bold, he was also realistic. When invited to discuss the chance of victory in a war against the United States, he’d told Prime Minister Fumimaro Konoe, “If we are ordered to do it, I can guarantee a tough fight for the first six months, but I have no confidence as to what [will] happen if it went on for two or three years.”
¹⁶

The recent successes at Pearl Harbor, the Philippines, and Malaya had so exceeded expectations that the Japanese were feeling
sensho-byo
, or victory fever. Yamamoto remained calm despite the excitement over Japan’s initial victories and counseled his officers to do the same.

“This is an all-night game of mah-jongg where you play until someone collapses,” he warned. “Just because the wind was in our direction … doesn’t mean we can relax.”
¹⁷

Clearly, Yamamoto’s gambling instinct had resulted in victory at Pearl Harbor. By taking the battle to the enemy’s doorstep, he’d achieved unprecedented success.
^†
His strategy ran contrary to two of the IJN’s strongest tenets: that a decisive naval battle should be conducted at sea, and that the bigger the battleship the better. Pearl Harbor had involved aircraft carriers, not battleships,
and the decisive battle had taken place in the sky over the enemy’s home anchorage, not at sea. Now it was time to take his logic one step further.

The United States had already boasted that if it came to war, it would reduce Japan’s wood and paper cities to ashes.
¹⁸
American cities might have been made out of concrete, but Yamamoto thought the strategy had merit.
¹⁹
As he told his commanders that day aboard the
Nagato
, “If we send a submarine aircraft carrier to the U.S. mainland and drop bombs like rain over their major cities, the American people will surely lose their will to fight.”
²⁰

Naturally, the right target selection was key to achieving the desired effect. The cities had to have enough political, economic, and symbolic importance to persuade Americans that continuing the war would be too painful. Certainly bombing Washington, D.C., and New York City fulfilled these criteria. Yamamoto had visited both places and knew the important role they played in America’s self image.

Yamamoto also knew that an air raid was unlikely to cause substantive damage—Japan couldn’t muster enough resources for that. But the psychological effect would be devastating, especially since there’d be no trace of the attacker. Yamamoto would not only hit a proud country in her two most important power centers, he would demonstrate yet again what the Japanese people were capable of. American leaders had badly underestimated Japan once before. Would Americans tolerate a second such mistake?

Obviously, long-range bombers were required for an attack, but Japan was too far away to launch a successful air strike. Since they’d never slip another carrier task force past the United States without being discovered, Yamamoto’s commanders discussed alternatives. The only IJN weapons platform that carried planes besides surface ships were submarines, but no submarine had ever been built with the capabilities Yamamoto required. Such a sub would need a long range to reach America’s east coast and return without refueling, a journey of nearly 38,000 nautical miles. The sub would also have to be large enough to carry at least two bombers and serve as a stable platform for launching the planes.

Though IJN subs had been carrying aircraft for more than two decades, and nearly 20 percent of all Japanese subs were equipped to carry seaplanes, none of the Sixth Fleet’s aircraft were suited for the task. The most common sub-borne plane, the Yokosuka E14Y1 floatplane, was used for reconnaissance. Its cruising speed was only 90 mph, making it easy pickings for enemy fighters. Besides, its bomb payload was tiny. Sending the Yokosuka to attack New York would be like sending a gnat to sting a bear. Importantly, IJN subs carried only a single plane, hardly enough to inflict psychological damage on a major U.S. city.

As they worked through the requirements, it soon became apparent that neither the right kind of plane, nor the right kind of submarine, existed in the Imperial Japanese Navy. That meant both weapons had to be designed from the ground up. This was asking a lot, given the competing demands the IJN faced for men and materials. Building these weapons would not be easy.

But Yamamoto was an innovative thinker. He appreciated novel ideas. He’d been one of the IJN’s first officers to see the potential for naval aviation, at a time when most of his colleagues put their faith in big guns and super-size battleships.
²¹
Yamamoto was not a submariner though. He’d had little direct experience with the submarine force and virtually no exposure to the design and construction of submersibles. He had a limited understanding of what could be achieved.

Sometimes, a lack of preconceived notions can lead to an unexpected breakthrough. As commander in chief of the Combined Fleet, Yamamoto had every right to ask whether an underwater aircraft carrier could be built with enough range and cargo space to carry and launch attack planes against the east coast cities of the United States. When it came to the answer, Yamamoto turned to his senior staff officer and chief confidant, Kamato Kurojima.

The relationship between Yamamoto and Kurojima was an unusual one. Taciturn by nature, Yamamoto did not confide in many people. Kurojima was one of them. Yamamoto trusted his personal staff officer more than his own chief of staff. When the Navy Ministry’s Personnel Affairs Bureau tried replacing Kurojima with a new
officer, Yamamoto refused the change. This was highly unusual, given the rigid nature of IJN personnel decisions, yet Kurojima remained in place while Yamamoto’s chief of staff turned over many times.
²²

Kurojima’s special relationship with his boss caused jealousy among his peers. It didn’t help that Kurojima’s ideas could be as unconventional as Yamamoto’s. Because of his unorthodox thinking, Kurojima was nicknamed the “Weirdo Officer,”
²³
but there is little doubt he was a fierce advocate for Yamamoto. Together they presented a formidable front that IJN personnel both respected and resented.

One story avidly repeated in the Navy Ministry concerned how the Naval General Staff (NGS) had originally opposed Yamamoto’s Pearl Harbor attack.
²⁴
Yamamoto grew so frustrated with their conservative thinking, he sent Kurojima to tell the NGS officers he’d resign if they didn’t support his plan. That got their attention, and NGS approval followed shortly thereafter. It’s not surprising that when Yamamoto wondered whether an underwater aircraft carrier could be built, he sent Kurojima to find out.

Given Yamamoto’s triumph at Pearl Harbor, NGS staff officers had to take Kurojima seriously. This time when he appeared, they paid attention. On January 13, 1942, less than a month after Yamamoto had raised the idea aboard the
Nagato
, the NGS had “studied the plan” and arranged for a meeting with the Bureau of Naval Construction to discuss specifics.
²⁵

The NGS staff officer in charge of submarines was Lt. Cdr. Tatsunosuke Ariizumi. Ariizumi would eventually command the
I-400
subs, but his job, for the time being, was to explore the idea with the IJN’s foremost sub construction expert, Ariki Katayama.
²⁶
Ariizumi and Katayama eventually agreed on specifications, yet what emerged was daunting. Yamamoto’s sub would have to travel nearly 40,000 nautical miles without refueling. By comparison, the farthest cruising range for an existing IJN submarine was 20,000 nautical miles, with a more typical range of 15,000, or less than half. A U.S. Balao-class sub like the
Segundo
had an average range of 11,000 nautical miles, so Yamamoto’s sub would have to have nearly four times the range of
an American submarine. Clearly, Yamamoto was talking about a sub of an order of magnitude bigger than anything ever built.

A sub this size would require 1,750 tons of fuel to circumnavigate the globe as well as enough provisions for four months at sea.
²⁷
(The average U.S. sub patrol was only 45 days.) Additionally, the sub would need room to carry two attack planes with a range of 600 miles, enough to reach the United States while carrying a single aerial torpedo, or the largest bomb in the naval aviation arsenal.
²⁸
The plane also had to be fast enough to evade enemy aircraft and be capable of the steep dive necessary for attack.

Finally, the sub would need a watertight hangar on its deck big enough to house two aircraft. The hangar alone would have to be at least 100 feet long, have a big enough diameter to accommodate the diameter of an airplane’s propeller, and be made of material thick enough to withstand not only the crushing pressure of the sea but machine-gun bullets from enemy planes.
²⁹
As if this weren’t enough, a powerful pneumatic catapult would have to be designed for the heaviest weight ever launched from the deck of an IJN sub.
³⁰
And a collapsible deck crane capable of lifting a ten-ton airplane
³¹
was also needed to recover the attack planes and load them on board.

Despite its large size, the sub would have to be fast underwater. Seven knots
^‡
was almost as fast as a U.S. fleet sub,
³²
while her safety depth of 330 feet was slightly better than the “official” safety depth of a Gato-class boat.
³³
In addition to its plane-carrying responsibilities, the sub would have to carry offensive armament, including 27 Type 95 torpedoes and room to berth a crew of 147 to operate it.
^§
34
(This number would later be increased to 157.)
³⁵
By comparison, U.S. fleet boats carried only 80 men.
³⁶

Yamamoto’s new submarine would ultimately top out at 400 feet, 3 inches long and displace 6,560 tons submerged.
³⁷
This was three times the displacement of the largest boat in the American sub force at the time. Longer than a destroyer, Yamamoto’s sub was essentially the size of a small cruiser. It wasn’t an exaggeration, then, to say that Yamamoto was asking for something akin to a small underwater aircraft carrier.

Though Yamamoto was talking about building the largest submarine the world had ever seen, those involved realized that the conning tower, bridge, and deck hangar couldn’t be so big that they’d hinder the sub’s ability to dive or maneuver underwater. These goals were mutually exclusive, however. A submarine big enough to carry and launch two planes would have to be so big, its dive time would be compromised. And though size gave the sub an advantage when storing and launching its planes, it also made her a sitting duck.

The IJN had always built the largest possible weapons to offset treaty limits imposed by America, Great Britain, France, and Italy. For example, Japan built World War II’s largest battleships (
Yamato
and
Musashi
), aircraft carrier (
Shinano
), and heavy cruisers. Constructing the largest sub was a natural step.

Clearly then, Yamamoto’s submarine would have to break the conventional mold. And though some IJN officers saw it as an eccentric experiment, it wasn’t a crazy idea, because the Sixth Fleet had more experience loading aircraft onto submarines than any navy in the world. In fact, repurposing inherently defensive sub-borne aircraft as offensive weapons was new strategic territory. It was the same kind of unconventional thinking that had enabled Yamamoto to conceive of carrier-borne aircraft taking the decisive naval battle to the home anchorage of the U.S. Pacific fleet.

Yamamoto wanted his follow-up punch to Pearl Harbor to be a knockout. The resulting plan called for building 18 monster subs carrying a total of 36 attack planes.
³⁸
Original forecasts estimated it would take two years before the first sub was ready. This wasn’t fast enough, and Kurojima lobbied to shorten the construction period. Though no one knew how the Pacific conflict would progress,
it didn’t matter. The sooner Yamamoto’s
Sensuikan Toku
squadron (“Special Submarine,” abbreviated as
Sen-toku
)
³⁹
was ready, the sooner it could force America to the bargaining table.