Nevertheless, the majority of Americans had been surprised by the attack on Pearl Harbor. Many of them had to look it up on a map to find out where it was. But if U.S. politicians had owned up to their machinations, they shouldn’t have been surprised at all. America had consistently underestimated Japan—whether out of arrogance, ignorance, or ingenuousness, it was impossible to say. Now Japan would launch a surprise attack on the Panama Canal in the same spirit as the attack on Pearl Harbor. If everything went well, America would be caught off guard again, and the Imperial Japanese Navy would strike just as Funada imagined it: like a storm from a clear sky. It wasn’t just poetic, it was poetic justice.
The initial order for 44 aircraft included two trainers called Nanzan. Each Nanzan had hand-cranked landing gear rather than floats and dual controls for pilot training.24 Nanzan were meant to replicate the Seiran flying experience, with several important differences. The Nanzan’s lack of floats meant the plane flew faster. Though the vertical tail stabilizer was shortened to compensate, it still handled differently.25 Nanzan means “southern mountain,” but one source claims the plane was jokingly referred to as Serian-kai, which translates as “difficult childbirth.”26 Whether this name referred to the training experience or the problem-plagued production process is unclear.
Despite troubles with his first test flight, Funada fell in love with the Seiran. In his postwar memoir, he wrote, “I piloted many kinds of aircraft … [but] the Seiran’s … responsiveness and controllability was unforgettable. To me, it was a masterpiece.”27
This affirmation was to be echoed by many Seiran pilots, a testament to Aichi’s design skills. Ozaki and his team had not only built the world’s first sub-borne attack bomber, they’d built a plane that handled beautifully too.
* Funada recalls that it was the ailerons, or wing flaps, that were the issue. Other sources, however, suggest the problem derived from the length of the Seiran’s tail stabilizer, which led to overbalancing.
CHAPTER 12
THE PANAMA CANAL
WHILE SEIRAN FLIGHT TESTS CONTINUED, FUJIMORI WAS BUSY at the Naval General Staff conducting research on the Panama Canal. Second only to Pearl Harbor, the canal was the most ambitious military installation the Japanese had ever targeted. But a lot of details were unknown, including the canal’s design, construction, and defenses.
The first thing Fujimori did was to get his colleague, Technical Maj. Gen. Ariki Katayama, to assign him three of his most capable engineers. Their job was to analyze everything Fujimori could find about the canal. Information was understandably scarce; not only had the canal been built more than 25 years ago, it was on the other side of the world.
Fujimori’s first bit of luck came when a Japanese engineer who’d worked on the canal provided him with a set of blueprints.1 His next was when an NGS colleague told him about an American at the Ofuna prison camp who had guarded the canal. During questioning, the prisoner revealed that the canal had been heavily protected after the attack on Pearl Harbor, but once the war shifted in the Allies’ favor defenses had been relaxed.2
Fujimori and his team worked in utmost secrecy as they gathered information and quickly had a stack of documents more than a yard high. Weekly meetings were held in the NGS strategy room to review the canal’s topography and analyze its features.3 One thing they learned was that the canal had been built to last. Hit by an earthquake only four days after it opened, the canal was undamaged, even though the quake was bigger than the one that had helped devastate San Francisco in 1906.4
It had taken 34 years and two nations to build the canal.* The largest engineering project ever undertaken at the time, the canal was considered a technological marvel along with the Pyramids and the Great Wall of China. It had two major lock systems: the Pedro Miguel locks on the Pacific side and the Gatun locks on the Atlantic.†
Fujimori realized that the locks were the most vulnerable part of the system and investigated attacking them from either the Pacific or the Atlantic side. A Pacific attack would offer an underwater strike force the best chance of concealment, since it was the most direct route from Japan. But Fujimori estimated it would take only a month to repair the locks on the Pacific side. However, if the Atlantic locks were destroyed, it could take up to six months to fix the damage.5 Shipping would come to a standstill.
Destroying the Gatun locks wasn’t going to be easy. They were as much fortress as transit system. The three chambers were each 1,000 feet long, with concrete walls 45 to 60 feet thick.6 Also, the topmost lock was only 110 feet wide, less than three times a Seiran’s wingspan. Any plane coming in for attack would have a narrow margin for error.
But Fujimori wasn’t as concerned about the locks, which appeared indestructible, as he was about their gates. It was their gates that had to be destroyed. Each lock contained double gates 65 feet wide, seven feet thick, and varying in height between 47 and 82 feet.‡ 7 Built by a company specializing in steel bridge construction, the heaviest gate weighed 745 tons,8 two to three times heavier than any lock gate ever built.§ Load-bearing parts like hinges were cast from vanadium steel, a durable alloy used to make car engines.9 It would take more than one bomb to destroy gates like this.
Additionally, each lock had not just one but two sets of gates—one behind the other in case the first set failed.10 Each lock also had an intermediate set of gates for smaller ships, and there was even an emergency dam that could be lowered in case the gates failed.
One fact that improved their chances was that the lock gates were hollow.11 At least a bomb or torpedo wouldn’t have to punch through seven feet of solid steel. Nevertheless, destroying them would be a daunting task. At minimum eight main gates, three interim gates, and an emergency dam had to be broached to offset the system’s redundancy. Additionally, flying more than 30 attack bombers into such a narrow, well-defended area was asking for trouble. It would be hard enough getting the Sen-toku squadron within striking distance; concentrating all those bombers against three separate locks would be like Luke Skywalker flying against the Death Star.
Fujimori’s breakthrough came when he realized two important things: first, they wouldn’t have to destroy all the gates to put the canal out of commission, just the gates of the topmost lock. And second, the best way to destroy the lock gates wasn’t by using just bombs or torpedoes, it was by unleashing the power of Gatun Lake.
Normally, it took 26 million gallons to float a ship 85 feet above the Atlantic.12 All of this water flowed down from Gatun Lake, which sat behind the last set of gates of the topmost lock. If the Japanese could concentrate their forces against destroying the top gate, the gate opening onto Gatun Lake, then a torrential outpouring of water would drain into the Caribbean, destroying the other gates in its path. It was an elegant plan. At this time Gatun was the world’s largest man-made lake;13 it held millions of pounds of water pressure. The Seiran attack planes had only to release it.
Launching an aerial torpedo against a lock gate was a risky undertaking. Fortunately, static objects are easier to hit than moving ones, and nothing was more static than a 745-ton lock gate that was closed. With practice, they could learn to hit it accurately, but they’d have to get past the canal defenses first.
The Panama Canal was situated at one of the most strategic locations in the world, and the United States guarded it accordingly. Nearly 40,000 troops were based throughout the canal zone,14 and the Atlantic approach was mined. Antitorpedo netting and mine-detecting equipment in each lock made it almost impossible for sabotage to succeed. Major fortifications were located at Colón, Margarita Island, and Toro Point. Fort Sherman, the primary military installation, boasted the largest artillery in the U.S. arsenal,15 16-inch cannons comparable to the fabled guns of Navarone. With a range of 25 miles, it was a good bet the 11-gun batteries would prevent any battleship from shelling the canal.
But the greatest risk in 1944 was aerial bombardment. Low-altitude barrage balloons hung over the locks, supplemented by 60 square miles of chemical
smoke pots to obscure the canal from the air. Antiaircraft batteries were planted throughout the canal zone, and two long-range radar stations were set up on each coast. Finally, the United States had 634 searchlights to protect the canal from night attack and had built nine airbases and 30 aircraft warning stations, not counting newly constructed bases in Peru, Ecuador, Guatemala, Nicaragua, and Costa Rica.16
If that wasn’t enough, a 1,000-mile defense perimeter extended from the canal into the Caribbean and was continually patrolled by U.S. planes and warships. Even if the I-400 subs got close enough to launch an attack, it was unlikely the Seiran could reach the canal without being spotted.
As the weeks passed, Fujimori’s team developed a plan for attacking the Gatun locks. Since ships transited only during the daytime, a dawn attack would be best, when the gates were closed and defenses lax. It also made sense to bomb the canal during the dry season (January through April), when it would take longer to refill Gatun Lake.17 Finally, a combination of bombs and aerial torpedoes was proposed to destroy the lock gates.
Interestingly, the Seiran were to be abandoned after the mission, and their pilots rescued. This was not a suicide attack, however; the Imperial Japanese Navy wasn’t that desperate.18 Everyone would be coming home.
Fujimori reviewed his findings with various NGS officers to receive their endorsement. If anything, they wanted the mission hurried up. Though the final plan would be left to the Sen-toku commander, the attack was set for early 1945.19 That meant they had a year to get ready. It wasn’t much time, considering that none of the submarines were complete and that the Seiran weren’t even in production, but time was of the essence. And there were other problems.
U.S. submarines had so clamped down on ocean routes that few essential materials were making it to Japan. Steel was particularly in short supply, and naval construction was affected. The I-400 program was no exception. By October 1943 plans for 13 of the 18 I-400 subs were canceled due to shortages.20 This left only 5 subs: the I-400, I-401, I-402, I-403, and I-404, plus the I-13 and I-14.‖ The fact that 5 out of 18 I-400 subs survived the cutback signaled the importance of the mission. But it was still a blow to the program.
The rest of 1943 and early 1944 would be spent modifying and test-flying the Seiran. The planes had to be ready when the I-400 subs were deployed in January 1945. The big question though was whether the subs would be finished by then. It was difficult to answer given that they were still on the building ways. Fujimori’s job was to make sure they were finished on time no matter what.
Meanwhile, the Sen-toku squad’s future commander was about to undertake the most important assignment of his career.
* The French began excavating the canal in 1880, the United States finished the construction, and the first ship navigated it in 1914.
† Excavation for the Miraflores locks did not begin until July 1940 and was suspended for the duration of the war in May 1942.
‡ The tallest gates were on the Pacific side.
§ This gate was on the Pacific side.
‖ The majority of accounts indicate that by October 1943, the Sen-toku squadron would be limited to five subs. Nevertheless, it appears that construction was begun on the I-405, which would have brought the fleet to six subs. This discrepancy has never been adequately explained.
CHAPTER 13
ARIIZUMI
WHEN CDR. TATSUNOSUKE ARIIZUMI FIRST SPOTTED THE SS Tjisalak, the Dutch freighter was 600 miles south of Colombo, Ceylon (Sri Lanka). The 5,787-ton break bulk carrier was traveling unescorted, an invitation to trouble given Ariizumi’s orders to disrupt Indian Ocean supply lines. It was early the morning of March 26, 1944, and the Tjisalak was 19 days out of Melbourne. As dawn broke, the day promised to be fair, with light winds and a gentle swell. Fortunately for Ariizumi, the Dutch cargo ship showed no interest in zigzagging to avoid enemy subs.1
It must have been a relief to be out from behind a desk. After serving two and a half years on the Naval General Staff and nearly two years as senior staff officer for SubRons 8 and 11,* the Sen-toku squadron’s future commander finally had a sub of his own. It wasn’t Ariizumi’s first sub command; that had been the RO-33 before the war had begun.† But after three staff jobs, he was happy to have a line officer assignment again. Unfortunately, necessity had as much to do with it as choice. The Sixth Fleet was running out of sub captains.
Ariizumi’s new command was the I-8, a frontline fleet boat tricked out with everything she needed to wage war against the Allies. A 2,231-ton Junsen-class Type 3 submarine,2 she boasted a floatplane and a dual 5.5-inch gun mount.3 One five-incher was standard on Japanese submarines, two was unusual. There was no more powerful configuration in the Sixth Fleet.
Ariizumi was familiar with the I-8. He’d served as senior staff officer for her squadron in Penang. It also didn’t hurt that the Imperial Japanese Navy ran in his blood. The firstborn son of a lieutenant commander and a naval accountant,4 Ariizumi had attended Etajima, Japan’s elite naval academy.‡ Etajima had a profound effect on him. Both mentally and physically rigorous, it emphasized absolute obedience and left little room for individual initiative. It also made clear that there was no middle ground between victory and defeat, a lesson Ariizumi had absorbed.5
After graduating with Etajima’s fifty-first class, he served his naval apprenticeship aboard a variety of ships, including the aircraft carrier Akagi.6 Eventually, he enrolled in submarine school and worked his way up the ladder, including a stint aboard the I-3. When he showed promise, Ariizumi was admitted to Japan’s Naval War College,7 where only the top-performing officers were accepted. Attendance virtually guaranteed a senior position at the NGS and eventual command of an IJN warship.
After graduation, Ariizumi was assigned to the First Section, First Bureau of the Naval General Staff. First Section was considered the “brain” of the IJN.8 Responsible for policy and strategic planning, it was a chance for Ariizumi to operate at a senior level where political acumen counted as much as smarts. Though serious in manner and autocratic in style, he had two years to familiarize himself with the labyrinthine workings of the Naval Ministry. Since Japan was already planning for war with the United States, it was an important position.
Ariizumi’s most significant contribution as senior submarine staff officer was championing the inclusion of five midget subs as part of the attack on Pearl Harbor. They’d been a last-minute addition to the plan.9 Recently perfected, the two-man subs were to secretly navigate the entrance to Pearl Harbor, slip up its channel, and attack the U.S. fleet where it lay at anchor.
Yamamoto was not enthusiastic about the plan.10 First, he insisted that all midget crews be rescued when the mission was over. Then he worried the midget subs would accidentally betray his surprise and demanded they not attack until after the aerial bombardment had begun.
Ariizumi waited all day December 8 for news of the midget sub attack, but Yamamoto’s worst fears had been realized. At least one midget sub was detected before the aerial attack commenced. Though the Japanese maintained the element of surprise, Ariizumi’s “special attack group” had made a poor showing. Only one midget sub penetrated the inner harbor and fired a torpedo. The rest either got lost or were discovered and sunk. Nine of the subs’ ten crewmen were killed in the attack. The tenth was captured along with his sub, making him America’s first Japanese prisoner of war.
Despite the debacle, Ariizumi lobbied to credit one of the midget subs with sinking the USS Arizona (BB-39).
“The world will scoff!” Mitsuo Fuchida, the leader of the aerial attack against Pearl Harbor, responded.11
It was obvious that a midget sub couldn’t have sunk the Arizona, since she was shielded from torpedoes by another ship. This didn’t stop Ariizumi, and a midget sub was credited with sinking the U.S. battleship. Ariizumi succeeded in having nine of his dead crewmen promoted twice in rank and enshrined as war gods at Yasukuni temple. It was an amazing accomplishment considering no one really knew how the midget subs
had performed.
After the Pearl Harbor attack, Ariizumi became involved with Yamamoto’s I-400 subs. As senior submarine staff officer, he was responsible for shepherding them through the naval bureaucracy. Some people considered him the father of the Sen-toku squadron, an appellation he was proud of if not fully deserving of. Now, two years later, he was out from behind a desk and ready to do some torpedoing of his own.
Ariizumi launched his first “fish” when the I-8 was a mile away. The torpedo struck the Tjisalak’s port side, just aft of her bridge. The freighter was rocked by a huge explosion, followed by a geyser of spray. Moments later the ship took on a sickening list. As the Tjisalak heeled over 20 degrees, Ariizumi launched a second torpedo. The situation deteriorated rapidly after that. The Tjisalak settled so quickly,§ 12 her main deck was awash in no time.13 Unable to send out a distress signal, the captain gave the order to abandon ship.
The last to leave the sinking freighter were her gun crew, who jumped into the ocean only when the water reached their ankles. Ariizumi had mistaken their cannon fire for depth charges and had kept the I-8 submerged.14 But once the Tjisalak went down, there was nothing left to fear.
Most times an I-boat slipped away after sinking an enemy ship. It was a bad sign if one lingered. When Ariizumi surfaced his sub, he spotted lifeboats in the water and decided to investigate.15 Once the sail cleared the waves, he scrambled onto the bridge and ordered the machine guns manned. The I-8’s 25mm antiaircraft guns had been swapped out for 7mm guns while the sub was in Kure.16 The change had surprised the crew, which wondered why anyone would want to downgrade their armament.17
Ariizumi turned to Lieutenant Honda, his executive officer, and told him to muster all off-duty personnel on deck.18 Then speaking to his translator, Jiro Nakahara, Ariizumi directed him to address the lifeboats.
“Where’s the captain?” Nakahara called using a megaphone.
Operation Storm: Japan's Top Secret Submarines and Its Plan to Change the Course of World War II Page 11