Operation Storm: Japan's Top Secret Submarines and Its Plan to Change the Course of World War II (13 page)

Speeding up sub delivery certainly addressed one major concern: how soon the
I-400
S
could be ready to attack. Any sweeping policy review is bound to step on toes though. Kurojima’s persuasive powers may have been strong, but he didn’t have Yamamoto
to back him up. This meant he couldn’t throw Fujimori’s proposal into the lion’s den without socializing it first.

Kurojima worked hard to build consensus behind Fujimori’s findings. Lobbying NGS decision makers before any official discussion occurred, he slowly made progress. By the time he met with Miwa, his fiercest opponent, it took only 30 minutes to convince him to support the program.
¹⁰

A commonsense recommendation tied to a thorough assessment probably did as much to get the
I-400
program back on track as anything Kurojima said. Perhaps the smartest thing Kurojima did was to circulate the proposal for comment before bringing it up for official review. By the time he made his recommendation in August 1943, there were no serious objections.
¹¹

It was agreed that the
I-400
was to be finished before the end of 1943, followed by four subs in 1944, six subs in 1945, and seven subs in 1946.
¹²
Additionally, Aichi was urged to accelerate production of the special attack bomber to meet the new schedule.

Staggering production rather than finishing all 18 subs at once might have been a compromise, but it was necessary, given the need to redesign the expanded sub hangars and the increasing shortage of materials. Importantly, it showed that the program’s opponents would compromise if its proponents were willing to get practical. Everything was smooth sailing—save for one important change.

New York City and Washington were no longer the targets.

W
HEN
J
APAN LOST
Guadalcanal, she was gradually forced to withdraw from the Solomon Islands. Fujimori had witnessed the reality firsthand when he journeyed to Rabaul in August 1943.
¹³
From what he could see, the war situation was not encouraging.

Rabaul was one of the South Pacific’s most important naval bases. However, now that Japan’s defense perimeter was imploding, Fujimori could see it was just a matter of time until their southern defense collapsed altogether. But what if Allied supply lines could be cut? What if Allied resources could be squeezed the same way U.S. subs were squeezing Japan?

Fujimori first conceived of using the
I-400
subs to attack the Panama Canal while visiting Rabaul. Not only would such an attack starve the enemy’s Pacific war machine, it would buy Japan much-needed time to regroup, resupply, and strengthen her perimeter. It was the same kind of bold, decisive thinking that Yamamoto had demonstrated when he decided to attack Pearl Harbor. Therefore, when Fujimori returned to Tokyo, he argued against attacking the U.S. mainland, recommending instead that the
Sen-toku
squadron be directed against the Panama Canal.

“The most effective way to cut U.S. supply lines is to attack the canal,” he explained. “The underwater aircraft carriers are the most suitable weapon for the job.”
¹⁴

It’s reasonable to ask why the Japanese hadn’t already attacked the canal. The idea had been kicking around at least since the beginning of the war.
¹⁵
Nobuo Fujita had considered using a sub-borne floatplane to bomb the canal as early as January 1942. A flying boat had also been considered. When the Naval General Staff proposed attacking the canal, the Navy Ministry considered it a “novel idea” but rejected it as too difficult to execute.
¹⁶
Given the serious beating Japan was taking, the Panama Canal now seemed a logical target.

Not surprisingly, the NGS staff agreed.

N
AMBU COULDN
’
T BELIEVE HIS LUCK
. T
HERE IN THE MIDDLE OF
his periscope was every submariner’s dream: ten Allied freighters intent on crossing his path. True, four Royal Australian Navy corvettes accompanied them, but from what he could tell, he hadn’t been spotted.

It was late afternoon on June 16, 1943, and Nambu, now captain of the
I-174
, was on patrol between Sydney and Brisbane. Visibility was good, and the convoy was still 10,000 yards away, when he noticed that one of the ships was having trouble keeping up. Like a weak animal struggling to stay with the herd, it begged to be culled. Nambu ordered “down periscope” and began his attack approach.

Once he’d finished command school, Nambu was put in charge of a training boat. Teaching the next generation of submariners was important. Still, he was itching to get back to war.
¹
He finally got his wish five months later, when he was named commanding officer of the
I-174
, a frontline fleet boat. Built in Sasebo and commissioned in 1938, the
I-174
was an excellent boat for the future captain of the
I-401
to learn his trade. A
Kaidai
-class submarine with four torpedo tubes in the bow and two in the stern, she was 345 feet long and carried 70 officers and crew. Her previous CO, Lt. Cdr. Toshio Kusaka, was one of the premier sub captains in the Sixth Fleet. Nambu would cross paths with him again when Kusaka was appointed commanding officer of the
I-400
. Until then, it was natural that he should follow in Kusaka’s footsteps.

The
I-174
had departed Kure on May 5 after two months of training. Nambu flew a large paper carp from the sub’s periscope in honor of Boys Day.
²
It was his first war patrol as CO, and Nambu
wanted to inspire his crew. It was an appropriate symbol since the Japanese believed carp were strong enough to overcome any obstacle. He also hoped it would distract them from the nerve-wracking business of departure.
³

Though he loved his role as commanding officer, Nambu found leavings difficult. His mind inevitably turned toward his family, whom he often talked about to his crew.
⁴
He never forgot the time his wife, Yukiko, had come to see him before the attack on Pearl Harbor. She had come to Kure with their one-year-old son, Masamichi. They’d stayed together at a
ryokan
near the Yokosuka naval base,
⁵
and though he’d been happy to see her, it was difficult as well.

Yukiko was expecting their second child at the time. Unfortunately, Nambu could tell her nothing about how long he’d be gone, or when he’d return. After three years of marriage, Yukiko was stoic; like many officers’ wives, she didn’t reveal her feelings. Nevertheless, the visit had been fraught with an undercurrent of emotion since their second child would be born while Nambu was at sea.

Few words needed to be spoken, since Japanese culture had taught husband and wife how to read between the lines. Yukiko wanted to be strong for her husband. This meant not burdening him with tears or the many worries she must have had. Nambu understood all this, but the visit wasn’t easy.

When Nambu bade his pregnant wife farewell, she was framed in a doorway, their infant son cradled in her arms. He knew this might be the last time he saw his family, but it was his duty to fight for the emperor. As he walked away, it was difficult not to look back. Still, what would be gained by lingering?
⁶
It would only make things harder. Once he stepped outside the door, he resolved that only the mission would occupy his mind. This kind of leavetaking was not so much a hardening of heart as a focusing of purpose, and Nambu made a habit of it as the war dragged on. So much depended on how he performed that nothing could deter him. He had a job to do, and he’d trained long and hard to do it. There was no turning back.

Nambu’s latest orders were to disrupt supply lines between the United States, Australia, and New Guinea. If he succeeded, the United States would have difficulty maintaining her perch in the South Pacific. For the past five months, Sixth Fleet subs had wreaked havoc off the Australian coast. Results were so encouraging that the
I-174
had been ordered to join the fight.
⁷
Nambu wasn’t just on a hunting expedition—he’d been given a mission of strategic importance.

Nambu relayed the convoy’s range, speed, and bearing to his executive officer, who began to plot a firing solution. The convoy was too far away to do anything, but at least they had time to set up. Of course, Nambu had every intention of eluding the corvette screen. Meanwhile, the sub’s forward torpedo room prepared a reception.

When Nambu took his next sighting, he could see that in addition to the ten freighters, there were three American LSTs, or Tank Landing Ships. He kept the excitement from his voice as he informed his officers of this development. LSTs were the backbone of the Allied Pacific war effort because they delivered huge amounts of troops, cargo, and vehicles directly onto a beach. He couldn’t have asked for a better target.

When Nambu had first arrived off the Australian coast, he’d been frustrated by a shortage of targets.
⁸
This probably had something to do with the successful number of sub attacks preceding his arrival. A crew’s morale depends on their captain’s ability to sink ships, though, and this made Nambu worry.

Just when he couldn’t take it any longer, they encountered the
Edward Chambers
, a U.S. Army transport.
^*
In his eagerness to score a kill, Nambu mistook the ship for a freighter and pursued it aggressively. Even though he couldn’t get closer than 20,000 feet, he refused to let the opportunity slip by. Finally, when he’d run out of
patience, he ordered the
I-174
to “battle surface.” Moments later the sub’s gun crew began lobbing shells toward the army transport.
^†
9

Nambu was certain at least one shell had struck the vessel. What he didn’t count on though was a “freighter” firing back. Twelve rounds from the
Edward Chambers
’s three-inch gun forced the
I-174
to submerge.
¹⁰
It had been foolish to make a surface attack in broad daylight.
¹¹
One well-placed shot into the sail, and the thin-skinned sub would have sunk. Nambu learned something important that day. He might have raised crew morale, but unless he set impatience aside, he wasn’t going to last long enough to sink many ships.

Things went better after that. Nambu fired four torpedoes at a commercial vessel off Sydney, two of which he believed struck home.
^‡
12
Now they were facing their largest convoy yet, GP 55 out of Sydney. Composed of 13 ships and five Australian corvettes,
¹³
the convoy was due in Brisbane on June 15.
¹⁴
It was Nambu’s job to make sure it didn’t arrive.

Two of the corvettes, the
Kalgoorlie
and the
Warrnambook
, patrolled the same side of the convoy as the
I-174
. The
Bundaberg
and
Cootamundra
patrolled the port side, while the
Deloraine
protected the straggler. Originally built as minesweepers, the Bathurst-class corvettes were too slow for convoy duty. Given the pressure that Sixth Fleet subs were exerting on supply lines, every available warship had been pressed into service.

As the setting sun outlined the convoy’s silhouette, the
I-174
easily slipped inside the corvette screen. The convoy’s weak link was the
Portmar
, a U.S. Army transport struggling to catch up. Nambu patiently waited for the transport to close the distance with another LST. When the two ships overlapped, he fired his first torpedo.

Two minutes later the stern of LST-469 erupted in an explosion, killing 26 men and destroying her steering gear.
¹⁵
Nambu thought
it a fatal blow
^§
and turned toward the
Portmar
with a second salvo.
¹⁶
The ship’s lookouts spotted his torpedoes and called for evasive action, but it was too late. A torpedo slammed into her number-one hold, igniting the ship’s volatile cargo of gasoline and ammunition. Moments after the torpedo detonated, the
Portmar
was engulfed by explosions. Seven minutes later, the transport was gone.
¹⁷

Cries of joy reverberated throughout the
I-174
.
¹⁸
Nambu had shown daring in sinking two ships. Unfortunately, the euphoria didn’t last. The
Warrnambook
and
Kalgoorlie
immediately began searching for the sub as the
Deloraine
stayed behind to pick up survivors.

Nambu dove to 250 feet, the sub’s safety limit, and was creeping out of the area when his sound operator reported approaching screws. Though the
I-174
’s crew did their best to remain silent, the
Warrnambook
found them anyway.

A depth-charge attack is terrifying for anyone who’s experienced it. When a depth charge detonates close to a sub, the concussion rocks the boat like a hobby horse. Gear and food stores rocket every which way, and it’s not unusual for paint chips to peel from the inside of a hull. Sometimes water or hydraulic lines burst, sending high-pressure jets spewing everywhere, and if they weren’t sealed quickly enough, electrical equipment shorted out and caught fire. It was especially dangerous when a sub’s cooling system was ruptured. Freon gas filled the interior, which could be fatal, and because Japanese hulls weren’t welded, sea pressure popped rivets like rifle shots. Woe unto the crewman who stood in one’s way.

The
Warrnambook
laid a pattern of depth charges perfectly mirroring the
I-174
’s escape route. Within moments they exploded with
all the fury of hell. Nambu’s crew could do little except watch their gauges dance. Many removed their sandals or took to their bunks to avoid making noise while imagining the next explosion a direct hit. As the sub’s interior temperature soared past 100 degrees, it became difficult to breathe, and the crew sweated profusely.