Operation Storm: Japan's Top Secret Submarines and Its Plan to Change the Course of World War II (20 page)

T
HE
S
EGUNDO
WAS
finally ready for commissioning on Tuesday, May 9, 1944. Fulp officially assumed his first command in a formal ceremony lasting only ten minutes. At the rate Portsmouth was turning out submarines, there wasn’t time for anything longer.

Ten days after he took command, Fulp took the
Segundo
out for
the first time.
²⁰
Five days later the navy’s Board of Inspection and Survey officially accepted the boat into the U.S. submarine force.

Fulp spent the next few weeks running battle station exercises and torpedo-firing simulations. As his crew grew proficient, he progressed to high-speed maneuvers, including collision drills and dive alarms. Soon, the
Segundo
’s crew developed the speed and confidence Fulp was looking for.

The men weren’t beyond getting in trouble though. Some of the more curious wondered what the colorful buoys were in the harbor. When they hauled one up and discovered it was a lobster trap, they began nightly raids to supplement their dinner. Only when they learned that lobster thieves are treated in Maine the same way cattle rustlers are in Texas did the practice stop.
²¹

Finally, the
Segundo
departed Portsmouth for the Naval Torpedo Station near Newport, Rhode Island. After taking on a load of “fish,” Fulp’s fire control party practiced their attack approach in Narragansett Bay, launching 30 torpedoes in two days. As a reward, half the crew was given leave to enjoy themselves in Middletown. Unfortunately, they got into a brawl with the locals and returned to the sub with a variety of shiners. When Fulp learned his remaining crew planned revenge, he restricted all hands to ship.
²²

After the
Segundo
spent a week at New London, she was ready to head south to the Panama Canal. Transiting the eastern seaboard promised to be uneventful. U-boat sinkings had been a problem at the start of the war, but by June 1944 the situation was under control.

There were surprises along the way though. One evening while the
Segundo
was surfaced, one of her senior officers spotted a half dozen torpedoes heading for the sub. When he saw their wake, he cried out an alarm. The torpedoes turned out to be nothing more than playful dolphins. Needless to say, the officer took a ribbing.

Another day Ens. Rod Johnson had the four-to-eight-A
.M
. watch. Johnson was scanning the horizon when a sudden flash caught his eye. Training his binoculars off the port bow, Johnson saw the feathered wake of a long, thin periscope a few feet above water. No sub was supposed to be there, so Johnson immediately called for
a dive. Moments later the
Segundo
’s sound man tuned in to the receding vibrations of a sub screw. So much for being in safe waters. After that the
Segundo
began zigzagging.
²³

I
T TOOK THE
Segundo
only eight hours to cross the Panama Canal. By the evening of July 5, she was moored at the sub base in Balboa.
²⁴
The crew marveled at the Pacific’s 18-foot tidal spread, but they didn’t have long to relax. Fulp conducted sound tests the next day to check on their noise-reduction efforts. When it came time for torpedo attack simulations, he pushed his men even harder.

Balboa wasn’t all work and no play, however. When he wasn’t busy spotting periscopes, Ensign Johnson spotted a five-foot-long stuffed iguana in the Balboa officers’ club. Deciding it would look perfect in the
Segundo
’s wardroom, Johnson smuggled the reptile on board, along with a case of Old Grand-dad.
²⁵

Fulp left Balboa for Pearl Harbor on July 9. Drills were a daily routine along the way as he strove to build a proficient crew. It was slightly before noon on Tuesday, July 25, when the
Segundo
finally arrived at the submarine base at Pearl Harbor. After minor repairs, she underwent three more weeks of training. Finally, Fulp received orders for his first war patrol as captain of the
Segundo
.

In accordance with ComSubPac Opord 268–44, the
Segundo
was ordered under way as a member of “Wilkins’ Bears,” one of three wolf packs bound for patrol between Mindanao, the second-largest island in the Philippines, and the Palau Islands, 500 miles east. Admiral Halsey’s plan was straightforward: deploy ten subs in three wolf packs to sink any Japanese warships that interfered with the American invasion of Palau.
²⁶

It was time to see what Fulp’s crew had learned. They were finally going to war.

B
Y THE TIME THE
S
EGUNDO
LEFT PEARL
H
ARBOR ON HER FIRST
war patrol, Japan’s Sixth Fleet was so decimated, it threatened to disintegrate as a cohesive fighting force. During the three-month period the
Segundo
crew underwent training, Allied antisub patrols sank 25 Japanese subs.
¹
This was practically half of all remaining Japanese subs, which left only 26 fully operational boats in the entire force. Considering there had been more than twice as many subs at the start of war, the Sixth Fleet was rapidly declining.
²

May 1944 was an especially horrendous month. While Captain Fulp was preparing the
Segundo
for shakedown trials, the USS
England
(DE-635), accompanied by the USS
George
(DE-697) and USS
Raby
(DE-698), used ULTRA intelligence and a new weapon called a Hedgehog to locate and sink six Japanese subs in a row.
³
The boats were stationed in a picket line 30 miles northwest of New Ireland when the destroyer escorts found them.
⁴
The
England
had already helped sink the
I-16
on May 21. The next day they located the
RO-106
and sunk her as well. Using the Hedgehog, which launched contact-exploding depth charges in a circular pattern, the three escorts worked their way down the Japanese sentry line. Later that same day they found and sank the
RO-104
, followed by the
RO-116
, the
RO-105
, and the
RO-108
. By this point, Japanese intelligence had picked up so many U.S. naval messages boasting of a clean sweep that they hurriedly signaled the last two boats to disperse.
⁵
Later U.S. naval forces concluded that the six-sub sinking was the most brilliant antisubmarine operation in history.
⁶
If lost crews could speak, they might have found
brilliant
an infelicitous word choice, but it certainly exemplified shortcomings in Sixth Fleet sub tactics.

As far as Nambu was concerned, sentry lines turned subs into sitting ducks. He’d even protested against them during a January 1944 conference at Truk. The loss of six subs had proved him right, but at great cost.

Unfortunately, the loss in May was nothing compared to the disaster that followed in June. The IJN was still preparing for the decisive naval battle, even though the location kept shifting closer to Japan. The situation worsened when the IJN High Command made a stupendous miscalculation by predicting the final battle would occur near Palau in the Caroline Islands. Instead, U.S. naval forces invaded Saipan, Tinian, and Guam nearly a thousand miles to the north, taking Japan completely by surprise.

The Allied assault on Saipan began on the morning of June 11, 1944, and Vice Adm. Takeo Takagi, CINC of the Sixth Fleet, immediately ordered his subs to head north to the Mariana Islands. Unfortunately, by the time they arrived, U.S. antisub forces were waiting. Eight more subs were lost due to the efficacy of Ultra intelligence and disorganized dashing about at the behest of Sixth Fleet higher ups.
⁷

Additionally, the U.S. invasion took a devastating toll on the Sixth Fleet command structure, which happened to be located on Saipan. Admiral Takagi had based his headquarters on the island, thinking it an ideal location from which to direct his sub squadrons’ southern arm. Now Takagi found himself under attack by Allied invasion forces. Abandoning his headquarters, he and his staff fled into Saipan’s mountainous jungle. This brought an abrupt halt to sub operations, which had to be transferred to Truk, where SubRon 7’s Rear Adm. Noboru Owada took over. Owada immediately called for the rescue of his commander in chief, so subs were sent to evacuate Takagi. They never stood a chance. Saipan’s surrounding waters were so choked with Allied forces, it was impossible for a boat to approach the island, let alone effect a landing.

Takagi called off his own rescue on July 2. Four days later he sent his final message:

That was the last anyone heard from Takagi. The Sixth Fleet’s commander in chief, the third CINC in three years, was presumably wiped out along with the rest of his staff in the ensuing charge. Three thousand Japanese soldiers, sailors, and airmen fought to the death on Saipan. The enemy bloodbath was so remarkable that even the U.S. Marines were impressed.

After the Sixth Fleet’s humiliating defeat, the IJN’s image reached an all-time low. Vice Adm. Shigeyoshi Miwa assumed command of sub operations in mid-July. Losses were so catastrophic, he didn’t have much to work with. The fall of Saipan, Tinian, and Guam meant Japan would now be in range of the B-29 Superfortress, a high-altitude bomber developed specifically for attacking Japan.

Miwa had served as a Sixth Fleet squadron commander at Pearl Harbor. He was experienced, pragmatic, and under no illusions as to what he’d inherited. To anyone else, the situation would have seemed hopeless. Nevertheless, Miwa, like the IJN High Command, was determined to fight.

One reason Allied naval forces were having such success in the Pacific had to do with Ultra intelligence. The other reason was radar. By 1943 every U.S. sub was equipped with radar, but Japan didn’t begin installing the new invention until 18 months later, and even then it was an inferior version. U.S. radar was able to detect Japanese planes, ships, and submarines at a far greater distance than Japan could spot U.S. forces. And when Americans applied radar to fire control, its effectiveness was devastating.

The loss of Saipan had major repercussions beyond crippling the Sixth Fleet. The Allies had called for unconditional surrender. Now it wasn’t just a case of playing defense; Japan’s survival
as a nation was at stake. This contributed to a dramatic change in strategy. Whereas Japanese naval forces had bravely defended the homeland by engaging the enemy with an array of modern subs, planes, and ships, these forces, and the well-trained men needed to guide them, were in increasingly short supply. What had seemed unthinkable to many in the high command six months ago would now become the strategy of last resort.

The impact of this change would be enormous for the
Sen-toku
squadron. Though still under construction, the
I-400
subs faced a seemingly impregnable Panama Canal; meanwhile the Allies were moving so close to Japan that Imperial military forces were being either methodically destroyed or hopelessly left behind. Importantly, the advent of radar combined with the use of Ultra intelligence meant the Allies knew virtually every move a Japanese sub would make. Though construction of the
I-400
subs and their
Seiran
cargo remained a secret, it didn’t take a psychic to guess that all would become known once the subs were operational.

Sixth Fleet activity dropped nearly to zero in late summer 1944, while Japanese subs were finally equipped with radar. This meant the chances of the
Segundo
meeting an I-boat on her first war patrol were small. Miwa wanted his subs in the safety of Japanese waters while he used the waning summer to develop a new strategy. How much longer Japan’s home waters would remain safe was an open question. Regardless of the answer, Miwa needed time. By September, the Sixth Fleet was again ready to prosecute the war with a new strategy that would unnerve the Allies. Japan was preparing to launch her first wave of suicide attacks. Sixth Fleet subs would be the tip of the spear.

U
NFORTUNATELY FOR
N
AMBU
, it was back to being a mole. After a brief time captaining a combat sub, during which he’d nearly been sunk several times, he’d been reassigned to outfitting the
I-362
. It was the exact same role Fulp had had at Portsmouth, except that the
I-362
wasn’t a combat sub—it was the first in a new line of underwater cargo carriers that Fujimori had recommended.

Nambu left Kure on the
I-362
’s maiden voyage. It was August 23, 1944, just days before the
Segundo
left Pearl Harbor for the South Pacific. The first thing Nambu noticed, once he’d gotten under way, was just how shoddily built his new sub was. The bridge vibration was so strong that a lookout using high-powered binoculars couldn’t see a thing because his body shook so much. This was a serious problem, since lookouts were as important to a sub’s survival as radar and often more reliable.

Nambu knew the problem could be solved by adding steel plate to the bridge, but he might not have appreciated just how little steel plate there was to be had. U.S. submarines had cut off Japanese supply routes, and few ships bearing raw material were getting through. The situation was bad enough that by 1944 the Japanese government was taking metal coins out of circulation and melting them down for reuse as war matériel. A decree had even been issued declaring all metal pots, pans, and utensils property of the state, and they were collected as part of a national scrap drive.
⁹
Since Japanese shipyards were running low on steel, they had no choice. They had to cut corners.