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

by John Geoghegan

  The main problem was chemistry. It wasn’t just that their styles clashed; the two men’s personal philosophies were fundamentally different. Ariizumi was a task-driven martinet, focused solely on the mission. Nambu, however, could see the big picture. Whereas Ariizumi wouldn’t think twice about sacrificing his men in pursuit of a goal, Nambu had his crew’s welfare at heart. It wasn’t easy for a broad-minded man such as Nambu to serve under a narrow-minded one like Ariizumi. But Ariizumi was Nambu’s commanding officer. He had to ignore the differences.

  Nambu grasped the ladder in the control room and climbed into the conning tower. The I-401’s sonar operator was reporting numerous contacts, so Nambu raised the sub’s periscope to have a look around. They were approximately two weeks out from Ominato, but as Nambu looked through the eyepiece, he was shocked by what he saw.

  There were so many American warships heading west toward Japan, the sight was overwhelming. And the armada was so confident, it didn’t even bother to dim its lights at night.10 The size of the enemy’s fleet gave Nambu pause. Could Japan really expect to defeat such superior numbers?11 Given the countless U.S. warships he saw, Operation Storm threatened to become meaningless.

  Normally, Nambu didn’t think in defeatist terms, but what was the point of dying if it would have a negligible impact against the American Goliath? Every one of his men was prepared to lay down his life, himself included.12 But from what Nambu saw, the U.S. fleet could easily absorb their blow and still invade Japan. Nambu was a patriot, and he had no intention of standing down. Still, a seed of doubt had been sown. He shuddered to think what awaited his countrymen.

  The enemy armada forced the I-401 to remain underwater. With a submerged speed of only two to three knots, the sub fell farther behind schedule. Nambu worried they’d miss their rendezvous if they didn’t travel on the surface,13 but the farther south they moved, the more enemy ships they encountered.

  Ariizumi was concerned for a different reason. He feared the I-401 would be discovered. Discovery would mean death, so to avoid putting the mission at risk, Ariizumi decided to make a detour. The detour he proposed involved sailing east of the Marshall Islands before rendezvousing with the I-400 and heading to Ulithi.14 Naturally, Nambu protested the change. The detour would significantly lengthen their journey, costing them valuable time. Importantly, the warships they saw were probably coming from Ulithi. The sooner they attacked the island’s anchorage, the more ships they could sink. Finally, a detour didn’t necessarily mean they’d avoid enemy contact, particularly since the Americans were everywhere. Nambu argued to maintain course.

  But Ariizumi was as conservative as he was overbearing. Nambu found it maddening, though he hid his irritation. Arguing with Ariizumi never did any good. The pint-size commander just dug in his heels. After failing to change Ariizumi’s mind, Nambu ordered a new course. The detour meant a new rendezvous location, which would have to be radioed to the I-400. It’s doubtful Nambu felt comfortable with the plan. Then again, he had no choice. Those were the rules of command.

  NAMBU WASN’T ALONE in his suffering. Cdr. Tsuruzo Shimizu, captain of the I-14, had nearly lost his sub from a grueling depth charge attack that lasted a day and a half. Shimizu’s survival would add to his reputation as a lucky skipper. The I-13, however, had not been so fortunate. The sub had still not arrived at Truk, even though she’d left Ominato six days ahead of the I-14.15 Of more concern, nothing had been heard from her since July 16, five days after she’d departed. Operation Storm depended on the I-13 and I-14’s reaching Truk, getting their Saiun into the air, and reporting on conditions at Ulithi. It would be senseless to attack the anchorage if American carriers weren’t there. Nobody wanted to repeat the mistakes of Pearl Harbor.

  Nambu feared for the I-13’s safety, and with good reason. ULTRA intelligence had not only been tracking the I-13 and the I-14 since their refueling stop at Chinkai, it had more than 28 mentions of Ohashi’s sub in its contact logs.16 In other words, once Nambu radioed the new rendezvous coordinates to the I-400, the U.S. Navy would be there to greet them. They were sailing straight into an ambush.

  CHAPTER 31

  CROSSED WIRES

  THE I-14 ARRIVED AT TRUK ON AUGUST 4,1 AND FOR THE FIRST time in three weeks, her crew set foot on dry land. Shimizu was happy to have escaped the Allied dragnet and immediately sent a message to Sixth Fleet headquarters relaying his arrival.2 Unfortunately, Truk was not what he’d expected.

  What had once been the empire’s premier forward naval base was now a shambles. The harbor was filled with sunken ships, and the skeletons of burned out planes littered the airfield. Those who had known Truk in its glory days could only weep at its destruction.3 If this was what an island looked like when the enemy bypassed it, what was in store for Japan?

  Under the circumstances, Shimizu’s arrival was nothing short of miraculous. The I-14 should have been lying at the bottom of the ocean, a gaping hole blown in her side, but Shimizu had run the Allied gauntlet. Ariizumi’s snorkel may have had something to do with it; still, Shimizu wasn’t just lucky—he was competent as well.

  As soon as the I-14 docked at Truk, her crew sprang into action. First they unloaded the two Saiun aircraft. Next, the planes were assembled and flown over Ulithi.4 That same day Ariizumi received orders for another mission.5 It seemed premature to plan a second attack before the first one had launched, but the Imperial Japanese Navy was running out of combat units. After the I-400 and I-401 sent their Seiran against U.S. carriers, the Sen-toku force was to travel to Hong Kong and pick up a new ten-plane squadron.6 After refueling in Singapore, they would then return to Ulithi for a second attack.* 7 A contingent from the 631st had already been dispatched by submarine to help with preparations.8

  Given Ulithi’s heavy security, the odds the I-401 would survive the first mission were slim at best; a second attack had only a one-in-a-million chance. It wasn’t being outnumbered that put them at risk as much as a top secret U.S. intelligence operation called ULTRA, which had broken the IJN’s naval codes. The IJN’s high command refused to believe their codes had been compromised, but U.S. naval intelligence knew the whereabouts of virtually every remaining Japanese submarine. Fortunately, Ariizumi’s sub captains had maintained radio silence since leaving Ominato.9 There were a few exceptions, such as Shimizu’s message confirming his arrival at Truk. But by and large, the Sen-toku subs were absent from the airwaves, which made it harder to find them.

  Ariizumi was not out of touch with headquarters, though. Sixth Fleet communications were still broadcast, and the subs picked them up at night when they surfaced.10 Receiving a radio signal was far different from sending one though—it didn’t betray a sub’s location. Radio silence, then, was an important reason Nambu had made it this far. It also maintained the crucial element of surprise.

  WHILE THE 631ST readied ten Seiran for transport,11 Asamura worried about the combat readiness of his pilots. Sub crews were kept busy with myriad tasks. Even the Seiran maintenance workers had plenty to do. But Seiran pilots and their observers had no assigned duties on board the sub.12 As days passed, Asamura worried they were losing their edge.

  In truth, Seiran aircrews were nothing more than high-priority passengers being transported to launch coordinates. Other than maintaining careful watch over their aircraft, they had little to occupy them. Regardless, the I-401’s crew treated them like gods.13 Though it was good for morale, Asamura worried that three weeks of inactivity would hurt pilot readiness.14

  The pilots had lost their appetite, for one thing. They subsisted mainly on canned spinach, soy sauce, and ginger, hardly the breakfast of champions. Lack of exercise was another problem. The I-401 might have been big, but it was so crammed with men and supplies that the Seiran pilots spent most of the day either lying in their bunks or hanging around the radio shack.15

  Asamura passionately believed that the Arashi mission was their last chance for heroic achievement,16 so he decided to do what he did best: impose a strict regim
en.

  One of the first things Asamura did was have his pilots assigned to lookout duty.17 Searching for the enemy in darkness was one way to keep night flying skills sharp. Asamura didn’t want to rely solely upon a special hormone designed to improve night vision that would be injected before the attack.18 He also had his pilots rehearse takeoff procedures while sitting in the cockpit19 and held mission briefings using photos and a scale model of Ulithi’s anchorage.20 Finally, he initiated a calisthenics program, held on deck, to keep his men in shape.21

  It’s not unusual in Japan to drill men to the point where fatigue is a greater impediment to success than lack of preparedness. This wasn’t the case for Takahashi. He had it easy aboard the I-400. When he grew tired of lying in his bunk, he’d go to the radio room and listen to the broadcasts out of Sydney. Sometimes he’d chat with the communications officer.22 Despite the effort to fill his days, Takahashi still had plenty of time to think. One memory he may have avoided was the atrocities he’d committed while serving aboard the I-37.

  It was February 22, 1944, when one of the I-37’s lookouts spotted the British Chivalry, an unescorted grain carrier sailing between Melbourne and Abadan. The I-37 sank the merchant using a combination of torpedoes and deck-gun fire. When the Chivalry was gone, her lifeboats were beckoned and the ship’s captain ordered on board the sub. Takahashi had held a pistol while the captain was interrogated. He’d also relieved him of a briefcase full of jewels.23

  Takahashi knew SubRon 8’s policy was to execute survivors of ships they’d sunk. For justification, he was told Japanese women and children had been indiscriminately killed during the invasion of Saipan.24 The lifeboats were too close for the sub’s machine guns to be used effectively, so combat rifles were issued. Takahashi used his sidearm instead. At least 13 men were killed and five wounded.25

  The I-37 sank two more British merchants after that, killing their crews in a similar manner.† If Takahashi felt regret, he didn’t express it. Even the “Butcher” was penitent.

  AS ULITHI DREW closer, the Seiran pilots grew increasingly sentimental. Knowing their days were numbered, they dwelled in the past even as they drilled operational details into their heads. One of the popular songs of the era, “Cherry Blossom Classmates,” or Doki no Sakura, perfectly captures their mind-set. The song celebrates the friendship of two former classmates, now naval aviators destined to die in battle. Few things represent the Japanese view of life better than cherry blossoms, and the song expresses the wistfulness many Japanese feel about life’s beautiful and transitory nature.

  You and I, blossoms of the same cherry tree

  That bloomed in the Naval Academy’s garden

  Blossoms know they must blow in the wind someday

  Blossoms in the wind, fallen for their country

  You and I, blossoms of the same cherry tree

  That bloomed in the flight school garden

  I wanted us to fall together, just as we have sworn to do

  Oh, why did you have to die, and fall before me?

  You and I, blossoms of the same cherry tree

  Though we fall far away from one another

  We will bloom together in Yasukuni Shrine

  Spring will find us again, blossoms of the same cherry tree26

  In addition to being sentimental, the absurdly young Seiran pilots weren’t above wearing good luck charms. Their talisman of choice was the senninbari, or “stitches by a thousand people.” The senninbari was a plain cotton wrapper worn like a cummerbund around the stomach. Designed to ward off harm, it was made by a man’s mother, wife, or sister. The custom had been around since the Meiji era and was hugely popular. Even in the summer of 1945, women could be found on street corners politely asking passersby to contribute a stitch. When 1,000 stitches were collected, the senninbari was ready to be worn.27

  THE DAY AFTER Ariizumi received instructions for a second assault, the I-400 passed east of Saipan.28 It was just before dawn the morning of August 5, and the sub had recently finished charging her batteries.29 Shortly after Kusaka submerged, a malfunction in the maneuvering room’s electrical distribution panel caused it to catch fire. Sparks shot everywhere as the board began to burn. Moments later, the power went out.30

  Fire is the worst condition that a closed system like a sub can face underwater. It can’t vent smoke, precious oxygen is consumed, and the air is soon poisoned. Kusaka ordered the maneuvering room’s hatches shut and closed the I-400’s ventilation system, but noxious fumes had already spread.31

  His next action was to surface. Unfortunately, the morning sun revealed a U.S. task force on the horizon, so Kusaka had no choice but to submerge again.32 This time the I-400 descended out of control forcing her crew to grab hold of anything they could find while the sub sank by the stern. When a gauge showed them passing their safety depth, many feared the worst.33

  The blackout only compounded Kusaka’s problems. Without bilge pumps, which require electricity to operate, water built up in the maneuvering room. The water not only risked shorting out additional equipment, it was pulling the I-400 down at a steep angle.34 Fortunately, Captain Kusaka regained control before his sub reached crush depth, but they were hardly out of trouble.

  As the U.S. task force steamed overhead, the I-400 slowly began to expire. It’s hard to know which was worse: to die from asphyxiation or at the hands of a U.S. warship. Without ventilation, however, the temperature inside the sub soared, while the dimness of the emergency lights only added to the oppression.

  The air was so noxious, the crew’s eyes burned, their throats became sore, and many developed headaches.35 Those men who weren’t on duty took to their bunks to consume as little oxygen as possible.

  It took more than five hours to complete the repairs.36 Time passed so slowly, they must have felt they were already dead. By the time repairs were finished, the I-400’s oxygen had almost run out. Kusaka wasn’t sure whether the task force was still around, but he had to surface. When the I-400 broke through the waves, he was relieved to find the ocean clear.

  Meanwhile, the I-401 had also met the enemy. In fact, Nambu had encountered so many U.S. warships, he was forced to submerge up to ten times a day.37 This meant the detour Ariizumi had ordered was taking longer than anticipated. Unfortunately, there was nothing Nambu could do about it. Everywhere they went, an unbroken line of U.S. warships steamed toward Japan. Though it added time to their overburdened schedule, Nambu did his best to evade them.

  One morning Nambu bade Yata, his chief gunnery officer, to the conning tower to look through the periscope.

  “Hey, Shooter,” Nambu called, using Yata’s nickname. “Look here. We could sink any of these ships with a single shot!”38

  Nambu knew the I-401 had to remain concealed. Mole ops had taught him restraint meant survival.39 But it was frustrating just to watch.40

  WHEN KUSAKA HEARD that an atomic bomb had been dropped on Japan, he was more concerned about missing his rendezvous than about the devastation. Because of the delays, his rendezvous with Nambu had been pushed back.‡ 41 But when Kusaka surfaced at the location after sunset August 13, the I-401 was nowhere to be seen.42 Undaunted, Kusaka remained on the surface, expecting to receive the I-401’s identification signal at any moment.43 When dawn approached and the I-401 still had not appeared,44 he began to worry. Kusaka could have radioed his commander. But to do so might have given away his position. One thing he couldn’t do was remain on the surface. The area was swarming with enemy ships, and if their sharp eyes didn’t spot him, their radar would. The I-400 prepared to submerge.

  Kusaka hoped the I-401 was just delayed, but his chief navigator jumped to the more obvious conclusion.

  “Either I’ve made a navigational error, or the I-401 has been sunk,” he told Kusaka.45

  Unfortunately, after double-checking his calculations, the chief navigator concluded they were in the right place. That left only one explanation.

  The I-401 had been destroyed.

  * The
re is some confusion around this point. Some accounts suggest the Sen-toku squadron would bypass Hong Kong altogether and pick up its Seiran squad in Singapore when it refueled.

  † The ships involved were the SS Sutlej and SS Ascot.

  ‡ Takahashi mentions that the rendezvous was originally scheduled for August 12. Nevertheless, Nambu says the rendezvous was to take place on August 14 and Takahashi subsequently says the same thing. It appears the rendezvous was pushed back two days from the original plan. This is not surprising given the distance involved and the number of problems both subs encountered along the way.

  CHAPTER 32

  THE EMPEROR’S VOICE

  THE FIRST INDICATION THAT SOMETHING UNUSUAL WAS HAPPENING came a few days before the Segundo left Midway on her fifth and final war patrol. A U.S. carrier strike against Japan’s third-largest island was suddenly called off on August 5. Additionally, Admiral Lockwood had been told to pull back his submarines at least 100 miles from Kyushu’s coast.1 This was strange, considering U.S. forces had done nothing for the past year except press closer to Japan. If Lockwood’s subs were being withdrawn, something big was up.

  Five days later, on Captain Johnson’s thirtieth birthday, the Segundo departed Midway. Several officers had been lost to crew rotation during the sub’s month-and-a-half layover. New arrivals included Lt. (jg) C. A. Hennessey, Ens. R. S. Byers, and QM3c Carlo Michael Carlucci. Nevertheless, more than half the sub’s original crew remained on board since her commissioning. Among them were the sub’s XO, Lt. John “Silent Joe” Balson, and Lt. (jg) Lewis Rodney Johnson. Chief of the Boat Edward A. Russell had also been with the sub since the beginning, as had Chiefs Carl Stallcop and J. T. “Doggy” Downs. Together these six men had 30 war patrols under their belts. When you added seven more for Captain Johnson, the total was nearly 40. Whatever the crew might have thought of their “medal-waving” captain, the Segundo was a well-seasoned boat.