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

by John Geoghegan

  LET THIS DISGRACE BE HANDED DOWN AND SHARED BY OUR CHILDREN AND GRANDCHILDREN AS IT BECOMES A CORNERSTONE OF OUR HOMELAND.51

  Later that night Nambu shaved off his mustache. He felt no regret doing so, though it surprised his crew. He’d been growing the mustache since before hostilities began, and its loss was his way of saying the war was over. The crew understood Nambu’s action. They also grasped his intention to return them home safely. No words need be spoken. The loss of his mustache said volumes.

  Traveling on the surface both day and night, Nambu raced home to Japan. On August 26, all IJN warships were instructed to dispose of their weapons and hoist the black flag of surrender.52 Nambu had all documents collected, in keeping with the order. Everything from the important to the mundane—including the sub’s logbooks, code books, personal diaries, schematics, and navigation charts—was loaded into jute sacks and weighted with ammunition.53 Then, as the midday sun shone overhead, the crew began throwing bag after bag off the machine gun deck. Nambu watched the sacks splash into the kuroshio current. The water was so clear, he could trace each bag as it sank into the darkness.‡ 54

  Weapons disposal left Yata in a state of shock. As gunnery officer, nothing was worse than throwing munitions over the side. It made him feel numb.55 Inouye, the I-401’s sonar operator, was similarly moved. Chucking weapons overboard was such a painful reminder of defeat that he found himself crying.56

  Nambu waited until dark before disposing of their Seiran. The moon was playing hide-and-seek behind the clouds as the first airplane was rolled from the hangar. The aircrew left her wings folded, attached the plane to the catapult without floats, and launched her pilotless into the night sky. The first Seiran didn’t get very far before plunging into the sea. Rather than sink right away, she settled so slowly, it seemed as if she were putting up a fight. Nambu thought it the saddest sight he’d ever seen.

  Heiji Kondo was the aircraft mechanic responsible for the second plane. He felt nothing but respect for his charge. As a result, he couldn’t let her leave with a U.S. star on her wings. It would be embarrassing if someone found her. Besides, Kondo wanted everyone to know the Seiran had been a Japanese plane. Working quickly in the darkness, he and his maintenance crew painted over the blue and white star with a bright red Japanese sun. When they were finished, they launched their Seiran into the night, tears shining in their eyes.57

  Ariizumi accompanied the launch of each Seiran with a lone cry of “Banzai!” It only added to the tragic effect.§ 58 But something strange happened that night. As the third Seiran hurtled down the launch ramp, the plane seemed to resist leaving. A rooster tail of sparks followed in her wake, and after crashing into the ocean, she floated so close to the I-401 that Kondo felt she was trying to return home.59 It was a sentimental notion, but it didn’t last. After struggling to remain afloat, the final Seiran dipped beneath the waves. The storm that had once been intended for a clear sky vanished into the night.

  The I-400 also disposed of its weapons. Surfacing shortly after sunset, Kusaka’s crew began throwing sacks of documents overboard. Among them were Takahashi’s personal flight records. It pained him to throw them away. But since they tied him to the I-37’s massacre of Allied prisoners, he had no choice.60

  Next came the Seiran. A brief ceremony was held before the planes were launched. The aircrews lined up on the machine gun deck, tears running down their cheeks, before they punched holes in their planes’ wings and fuselage.61 Next the I-400’s crane picked up the planes, one by one, and dropped them into the ocean.‖ Even in darkness, the Seiran’s silver-painted body could be seen sinking slowly out of sight.

  It hurt to see such good aircraft destroyed. Still, Takahashi knew that disguising the planes as American would be seen as a violation of international law. But the I-400 was not home free yet. Amid all the hurried activity, a crewman fell overboard and drowned. It was shocking to lose someone so close to Japan, especially now that the war was over. The accident didn’t stop weapons disposal though.62 There was no time for delay.

  Seiran ordnance came next. One by one the 1,760-pound bombs were plucked off the deck and dropped into the sea.63 Okui, the cook, was sad to see the weapons go,64 but not as sad as the sub’s chief torpedo officer over what happened next. After launching the I-400’s bow torpedoes, Kusaka watched in dismay as one by one they leaped out of the water, turned in a half circle, and began heading back toward the boat.65 It took only one malfunctioning torpedo to sink a submarine; several was unprecedented. Clearly, the gyros had been set incorrectly.

  Incredible as it may seem, after surviving an Allied air raid, underwater mines, an electrical fire, and multiple navy task forces, the hunter was once again the hunted. Only this time, the I-400 wasn’t hunted by the enemy—she was hunting herself.

  * Accounts conflict, but it appears that the high command initially ordered the Sen-toku squadron to proceed to Kure. A subsequent order changed the destination to Ominato. See Nambu, Beikidoukantai wo Kishuseyo, p. 240; and Kazuo Nishijima, interview by author.

  † There is some dispute over whether Ariizumi argued initially for suicide or for heading for the Sanriku coast, where the crew would disperse. Having studied Ariizumi, I find it wholly within his character for him to have first supported suicide.

  ‡ One reason there are so many conflicting dates in the story of the I-400 subs is that most of the material that would allow for an accurate reconstruction of their timeline was disposed of in this manner.

  § Nambu thinks it may have been Asamura who cried “Banzai!,” but Asamura recalls it was Ariizumi.

  ‖ Takahashi, in Shinryu Tokubetsu Kogekitai (p. 208), says the Seiran were launched into the sea by catapult rather than dumped by crane.

  CHAPTER 34

  ESCAPE

  CARLO CARLUCCI WAS ASLEEP WHEN NEWS OF THE JAPANESE surrender first reached the Segundo. He’d finished his watch, had a bite to eat, and was sacked out in the crew’s quarters when somebody turned the lights on.

  “What’s up?” he asked drowsily.

  “War’s over!” someone shouted.

  Carlucci couldn’t have been more surprised.

  The Segundo was en route to the Kuril Islands when Japan accepted peace terms. It was 2:07 the afternoon of August 15 when the news came by radio. Forty-three minutes later it was followed by ComSubPac orders to cease fire.1

  As late as July 1945, U.S. submariners were repeating the hopeful slogan “The Golden Gate in ’48,” so it’s clear they thought fighting would last at least a little while longer.2 But the absence of enemy ships was one indication the war was near its end.3 The Segundo had seen nothing since leaving Midway. Still, as Captain Johnson approached their designated patrol area, he resolved to stay on guard. The Japanese might have accepted a cease-fire, but he knew how determined they could be. They’d have to be careful.

  The Kurils are a long chain of islands extending in an arc northeast from Hokkaido to the Russian peninsula of Sredinny Khrebet. Long contested, the islands were an uneasy mix of both populations. Russia had begun invading the chain three days after the cease-fire had been declared. The Kurils may have been economically insignificant, but they had strategic value, since they could be used to launch an attack against Japan.

  The Segundo patrolled the area for seven days. From what Johnson could tell, the Japanese were sitting out the Russian land grab. Given the animosity between the two countries, it must have hurt. Nevertheless, Johnson’s orders were to observe, not to intervene.

  On August 19 the Segundo approached close enough to photograph one of the islands.4 Seeing no activity, Johnson withdrew. That same day he stopped a Japanese fishing trawler. Deciding she wasn’t a threat, he let her go. It was a waste to interdict fishermen,5 and now that a cease-fire had been declared, he had no reason to sink one. In fact, Johnson became so confident, the Segundo remained surfaced by day, diving only when torpedo maintenance was necessary.

  The Segundo wasn’t alone on her patrol. The USS Ra
zorback was also in the area. The subs exchanged recognition signals and small talk, killing time until something more interesting came their way. Then finally on August 24, Johnson was ordered south to Tokyo Bay.6

  The Segundo was told to mop up any remnants of the Imperial Japanese Navy that were encountered along the way.7 There had been enough isolated attacks since the cease-fire to warrant concern. The official surrender ceremony had even been pushed back a few days to give the Japanese military time to persuade reluctant factions to lay down arms. Any more violations and the cease-fire might be jeopardized.

  Johnson knew enough to maintain a sharp lookout, but he probably didn’t expect any strays.8 Japanese warships weren’t anticipated this far north, and if he did see anything, it was likely to be a small surface vessel, since most capital ships had been sunk.

  But not all Japanese warships had been destroyed. The world’s largest, most secret submarine was returning home, determined that nothing should get in her way. What Johnson didn’t realize was that the Segundo stood right in her path.

  THE I-401 WAS considerably lighter after jettisoning her weapons. She now rode higher in the water than at any time since training. Her increased buoyancy also meant she traveled faster, a condition Nambu exploited in his race to get home. For the last two days, the I-401 had been making her way up Japan’s eastern seaboard. They’d managed to avoid the enemy thus far. But one dark night, when visibility was poor, they had a bad scare.

  They were still south of Tokyo when one of the lookouts spotted a shadow in the distance. There was little chance of it being a Japanese ship given all the enemy activity, so Nambu submerged, hoping to escape detection. As the I-401’s crew sat motionless, the sound of a U.S. Navy task force roared overhead. It would have been an excellent opportunity to attack if Nambu hadn’t already disposed of their weapons. When the propellers faded, Nambu resurfaced. He could still see the huge black shadows heading toward Japan.9 Ironically, it was the same direction he was heading in, only he wasn’t a conqueror as they were—he was a fugitive. The difference was incalculable.

  Avoiding capture was only one of Nambu’s problems. The other was Ariizumi’s increasingly erratic behavior. Just as the Segundo’s crew was watching Captain Johnson for signs of trigger happiness, Nambu watched Ariizumi for signs of trouble. Nambu no longer feared being killed in battle, and he was well aware that his commander had volunteered them for suicide. Since then, however, Ariizumi’s strange behavior had made him feel ill at ease.

  Nambu’s greatest fear was that the command structure was breaking down. The Seiran pilots had lapsed into a kind of despondency,10 and the rest of the crew was equally depressed. If morale collapsed, they could be in danger. It took only one mistake for a fatal accident to sink a submarine. Nambu had to find a way to keep that from happening.

  Ariizumi’s behavior wasn’t helping matters. It was shocking to see him look so poorly. The normally stout squadron commander seemed to have shrunk to half his normal size, and his clean-shaven face only emphasized the change. Even some of the I-401’s officers didn’t recognize him. After entering the wardroom, the I-401’s sonar operator thought, “Who’s that sitting there?” Then he realized, “It’s the boss!”11

  It must have been devastating for Ariizumi to see his world collapse around him. He’d single-mindedly served two things in his life: the emperor and the Imperial Japanese Navy. Now both had ordered him to surrender. To make matters worse, he was returning home not only in defeat but as a war criminal. No wonder death was an appealing solution.

  Ariizumi’s travails were far from over. As they neared Japan, he’d felt safe enough to report the I-401’s location. However, the Imperial Defense Command had forwarded the information to the U.S. Navy as part of the armistice agreement.12 It was the ultimate betrayal by the very system Ariizumi had pledged to support. Fortunately, Ariizumi had no way of knowing this—otherwise he might have taken precipitate action. In the meantime, he struggled to live within a code that fate had conspired to destroy. The truth must have been enough to drive him crazy.

  BY THE EVENING of August 28, the I-401 was less than 200 miles off the coast of Japan.13 In ten hours they would reach the Sanriku coast, their final destination.14 As it was, they were passing Kinkasan, a mountainous island northeast of Tokyo. Bando fantasized about evacuating the sub.15 In the ancient past, gold had been discovered nearby, and good fortune came to those who visited the local shrine. But the I-401 continued its journey.

  In addition to raising the black surrender flag, Nambu had also angled the deck guns downward to indicate they weren’t hostile. The I-401 may have appeared chastened, but neither Nambu nor Ariizumi was willing to hand their sub to the enemy just yet.16 It was miraculous that Nambu had gotten this far without being apprehended. In a sea brimming with enemy ships, it was virtually impossible to evade capture. Now, with his objective only ten hours away, Nambu imagined he could safely return his men to Japan. If luck would only hold.

  “Something black, fifteen degrees to starboard!” a lookout shouted. “Movement unknown!”

  It was near midnight when a silhouette unmistakably formed into a U.S. submarine. Radar Officer Natsume confirmed he had a ship on his screen. We can’t dive to escape, Nambu thought, they’ll see it as an act of aggression. The last thing he wanted, now that the war was over, was to lose his crew in a meaningless action. But he didn’t want to be captured, either. And so in what amounted to an act of wishful thinking, Nambu decided upon swift withdrawal.17

  Ordering a change in course, he felt the sub veer hard to port and accelerate to flank speed. As he watched the enemy fall away 90 degrees to starboard, he prayed they’d escaped without being discovered.18 Unfortunately for the crew of the I-401, Nambu’s luck had finally run out.

  CHAPTER 35

  INTERCEPTION

  THE SUB ROCKED GENTLY ON THE SURFACE AS DAWN SPREAD across the Pacific. The sea was calm, the day gray and hazy.1 As Nambu watched the American sub less than 500 yards off his starboard side,2 he didn’t need binoculars to see that her torpedo tubes were pointed directly at him.

  The confrontation had a rallying effect on the commander. Restored to his intransigent self, Ariizumi stood beside the I-401’s captain staring grimly at the Americans. Nambu requested an update on port engine repairs. Informed it would take a while longer, he reviewed his options. As best as he could determine, he had three—all of them bad. They could fight, they could run, or they could surrender.

  Yata, the chief gunnery officer, wanted to ram the American submarine.3 Nambu dismissed the idea, since they’d never close the distance before being torpedoed. In fact, attacking the sub was impossible. They’d disposed of all their weapons two days earlier. The Americans didn’t know this, of course, which meant Nambu could leverage their ignorance. But he wasn’t ready for a banzai charge, at least not yet, which left two other options: running or surrendering. Both were unappealing.

  As Nambu watched his enemy, the American sub flashed another signal. This one said “surrender.” “Stop” was one thing, “surrender” quite another. The I-401 might have been flying the black flag, but Ariizumi had no intention of honoring it.

  Asamura had been sleeping when the Segundo first appeared. Word of the American sub quickly spread, and though there was no panic, the crew was worried. Fearful of death, a young crewman sought Asamura out for reassurance: “We’ll die together, won’t we?”4

  The young man’s concern was indicative of the fear some felt inside the I-401. Many of the enlisted men expected to die, if not at the hands of the Americans, then at the hands of their commander. After all, everyone knew Ariizumi had slaughtered Allied prisoners. Their treatment at the hands of the enemy would be no different.

  Some men were convinced Ariizumi would never permit that to happen. He would kill them first, either by scuttling the sub or by ordering them to commit suicide. Either way, they were doomed.

  While the crew wondered what was happening, Nambu carefully wa
tched the Segundo. He had a bad feeling about the sub. Her intention to sink them seemed clear. Given his limited options, Nambu figured it was best to do nothing. A passive-aggressive approach might buy time to develop a course of action. He would wait them out.

  Unfortunately for Nambu, Captain Johnson was in no mood for stalling. He’d been granted permission to torpedo the enemy if they showed resistance. The Japanese sub might have been flying the surrender flag, but nothing in her behavior indicated she would do so.

  The Segundo’s crew knew their captain wouldn’t hesitate to sink the enemy. They might have been more worried, however, had they known his real intention. For Johnson wasn’t going to sink the I-401, at least not yet. He was going to try to board her first.5

  THE I-401’S CHIEF navigator, Muneo Bando, was standing near Captain Nambu on the bridge when they received a signal from the American sub to “dispatch an officer.”

  “Send an officer?” Bando thought, “What do they mean send an officer? They should send someone to us!”6 Even in the middle of a showdown, Sixth Fleet pride took precedence.

  Nambu tried a different approach. Instead of refusing the request, he signaled, “We have no boat.”7

  This wasn’t true, of course. Kondo, the Seiran mechanic, was busy preparing a rubber raft for just such a request.8 But Nambu was reluctant to comply with the order.9 The longer he dragged things out, the more options he might have. Though he didn’t want to be torpedoed, he wasn’t going to cooperate just because they’d asked.

  In the meantime, Captain Johnson was losing patience. “Tell them we’ll send a boat!” he snapped.