Operation Storm: Japan's Top Secret Submarines and Its Plan to Change the Course of World War II (21 page)

Nambu had only a month to train his crew, far less time than usual. A shortage of men and boats, and the increasingly dire fate of stranded troops, demanded he get under way as soon as possible. Nambu’s crew weren’t green only from inexperience; they were green from seasickness as well. He intended to overcome their deficiency through intensive drilling, but an inexperienced crew wasn’t his only handicap. Compared to the
I-174
, the new sub was a “tortoise,”
¹⁰
built for transport rather than speed. If that wasn’t bad enough, the sub’s radar was faulty.
¹¹
Nambu tried not to let it bother him—he swallowed the bitterness and pressed on. Every time he turned around, however, something seemed to break down. It was not an auspicious beginning for a new sub.

Nambu couldn’t help but wonder about the wisdom of the Japanese High Command. At the beginning of the war, the IJN had performed well and achieved much. But did Imperial forces really have to be spread so thin? Had anyone ever thought how to supply such a vast network of men? The obvious lack of planning
disturbed him. A submarine was best suited for cutting enemy supply routes, not for transporting cargo. He couldn’t forgive those in the Sixth Fleet who preferred to use a submarine as a mole rather than to attack the enemy.
¹²
Something was wrong.

After resupplying the 4,000 stranded troops on the Micronesian island of Nauru, Nambu sailed for Truk, where things were not much better. Once home to the Sixth Fleet and Yamamoto’s principal headquarters, Truk was eerily quiet. Nambu could see that the island had been left to wither on the vine. The emptiness was chilling.
¹³
The message from Tokyo was that they could still win the war. For anyone in the field the evidence was in stark contrast.

The truth of the matter was that by the fall of 1944, the mortality rate for Sixth Fleet submarines was astronomical. By the end of the war, nearly 100 subs would be sunk, virtually the entire Japanese sub force. Even by September 1944, many of Nambu’s colleagues were dead, and given the way things were going, he could expect to join them soon. It was Nambu’s duty to show courage in the face of despair. Though outwardly he maintained his resolve, inwardly he had his doubts.

By the time Nambu returned to Kure, Japanese military strategy had radically changed. The loss of Saipan, followed by the successful U.S. invasion of Ulithi, put U.S. fighting forces in uncomfortable proximity to Japan. Ulithi, a previously unknown backwater in the Caroline Islands, boasted the world’s fourth-largest lagoon. It was a natural staging area for the U.S. invasion of the Philippines and Japan. Combined Fleet Headquarters decided that the best way to delay an invasion would be to launch an attack on Ulithi. Two Sixth Fleet subs were charged to carry out the mission. While Nambu awaited orders, modifications began on a new breed of suicide sub.

After spending two months outfitting the
I-361
(yet another cargo carrier), Nambu was relieved of command and ordered to Sasebo.
¹⁴
He was finally getting his wish. He was being made captain of an offensive submarine, a brand-new boat so secret that nobody knew its designation. It was no ordinary sub. It was the
I-401
, the flagship in a new series of boats called the
Sen-toku
, or “special
submarine” squadron. Conceived by Admiral Yamamoto to attack New York City and Washington, thereby changing the course of the great Pacific war, the
I-400
s
’
current mission was to bomb the Panama Canal.

But Nambu wasn’t the only Sixth Fleet officer entrusted with this game-changing assignment. A commander had been put in charge of the attack squadron. He was so well regarded that many considered him the only officer to be reliably entrusted with such an audacious task, a mission so freighted with importance that the top naval command were the only ones who could green-light it.

As Nambu would soon learn, his new commander, fresh from the Indian Ocean, was Tatsunosuke Ariizumi. It was a personnel appointment that would change his life.

IMPERIAL JAPANESE NAVY
I-401
SUBMARINE - 400 FEET

IMPERIAL JAPANESE NAVY
I-14
SUBMARINE - 373 FEET

U.S. NAVY FLETCHER-CLASS DESTROYER - 376 FEET

U.S. NAVY BALAO-CLASS SUBMARINE - 312 FEET

T
HE
I-8
DOCKED AT
Y
OKOSUKA
N
AVAL
B
ASE ON
O
CTOBER
9, 1944.
¹
The
Sen-toku
squadron was in the final stages of construction when Ariizumi left his sub for the last time and hurried to Tokyo to be briefed by Yasuo Fujimori of the Naval General Staff.
²

Ariizumi knew the
I-400
subs were a career-making assignment. Many in the Imperial Japanese Navy considered attacking the Panama Canal to be as important as the latest suicide weapon, a human-guided torpedo called a
kaiten
. Executed properly, the
Sen-toku
attack might help Japan fend off defeat. Ariizumi felt honored to be given responsibility for such an important mission.

The
I-400
subs were to be organized into Submarine Squadron 1 (SubRon 1) and based in Kure. SubRon 1 was the only Sixth Fleet squadron consisting entirely of subs—no surface flagship or tender would be needed for their mission. Initially, SubRon 1 would consist of four subs: the
I-400
and
I-401
and the
I-13
and
I-14
. If all went well, three of the four subs would launch before the end of the year, with the
I-14
following shortly thereafter.

As Fujimori described it, the amount of men and matériel allocated to the program was nothing short of incredible. Nearly 600 submariners would man the four subs. The
I-400
and
I-401
alone accounted for more than half that number. This didn’t include their
Seiran
pilots and observers, or the maintenance technicians, ground crew, and armorers needed for land and sea assignment. In other words, the underwater aircraft carriers and their support personnel totaled nearly 1,000, almost as many men as were found in the average Japanese infantry battalion.

The amount of manpower necessary to construct the
Sen-toku
squadron was equally enormous. So great were the resources required to build four submarines that three separate naval yards were employed, both military and civilian. Supplying steel created such a drain on Japan’s shipbuilding program that naval higher-ups constantly complained about the shortage.

And that wasn’t all. There were four additional subs in various stages of completion: the
I-402
would be ready by July 1945, and the
I-404
(the next furthest along) would follow later in the year. As for the
I-403
and
I-405
, the former was in the early stages of construction, while the latter hadn’t been built yet. As for the 12 remaining boats
I-406
through
I-417
, they were paper subs only. They’d never got past the planning stage.

The resources devoted to the
Sen-toku
subs were astonishing given the damage the Japanese war machine had sustained. It signaled just how strongly the NGS believed in the mission.
³
Japan’s defense perimeter may have been crumbling, but if the subs could destroy the Panama Canal, thereby stopping war matériel and reinforcements, they just might prevent compliance with the Allied demand for unconditional surrender.

Ariizumi was glad to hear that his subs were nearing completion, but he must have felt concern as to whether there would be enough time both for sea trials and for a full training schedule. The earliest he could start would be around the New Year. Given how poorly the war was going, his squadron would have to rush to get ready.

After meeting with Fujimori, Ariizumi went to Shizuoka to spend a few days with his wife, Matsu, and their five children.
⁴
It’s reasonable to assume he was glad to see them after such a long absence. Ariizumi may have been a war criminal, but he still loved his family. Not much is known about this visit except that he drank heavily during his stay.
⁵
Whether it was to relieve the stress of the Indian Ocean massacres, to celebrate his new appointment, or just because he liked to drink, we can’t know for sure.

Ariizumi could be touchy, though. On a previous home visit, Matsu had served grilled sea bream the night before his sub was
to leave. When Ariizumi ate only the bottom portion, she made the mistake of serving him the remainder for breakfast. When Ariizumi saw what she’d done, he erupted.

“I’m about to go on a boat!” he shouted, throwing his plate on the floor. “It’s bad luck to serve fish with no bottom!”
⁶