Killer Subs in Pearl Harbor

The stealth attack of Pearl Harbor by Japanese midget submarines is a little known story of WWII. Airing May 23, 2012 at 9 pm on PBS Aired May 23, 2012 on PBS

  • Originally aired 01.05.10

Program Description

(Program not available for streaming.) NOVA dives beneath the waters of Pearl Harbor to trace provocative new clues to one of the most tragic events of World War II—the sinking of the USS Arizona. More than 1,000 crew members perished in the greatest single loss of life in United States naval history. For decades, it has been thought that a bomb dropped by a Japanese aircraft sank the Arizona. But the discovery of a group of Japanese midget subs in and around Pearl Harbor has raised questions about the battleship's final hours.

NOVA's team of expert investigators journey to the seafloor to explore the wreckage of the most mysterious of these subs. Did this mini-sub and its two-person crew make it into Pearl Harbor and fire torpedoes at the Arizona? They pursue this puzzle with unprecedented access to the remains of the Arizona and other unique evidence, including aerial photos taken by Japanese aircraft and moving testimonials from U.S. and Japanese veterans. "Killer Subs in Pearl Harbor" is a gripping investigation of the possibility that these tiny but lethal mini-subs may have played a crucial and previously unsuspected part in the tragic events of that "Day of Infamy."


Killer Subs in Pearl Harbor

PBS Airdate: January 5, 2010

NARRATOR: An expedition is underway, and it may rewrite the history of the Japanese attack on Pearl Harbor, a day that forever lives in infamy.

FRANKLIN ROOSEVELT (President of the United States, 1933–1945, Radio Address): ...December 7th, 1941, the United States of America was suddenly and deliberately attacked.

JOHN CHATTERTON (Wreck Diving Expert): This is the exact moment when the United States was drawn into World War II. You would think that we would know just about everything about this attack. We don't.

NARRATOR: Most people think of the surprise attack on Pearl Harbor as an aerial assault raining down from the sky. But now the mysterious wreck of a Japanese submarine, missing for almost 70 years, has been found in the waters just outside Pearl Harbor. Could the attack have also come from below?

LORI JOHNSTON (Microbial Ecologist): It's my conclusion that—after analyzing the data—that this sub fired its torpedoes prior to its sinking.

PARKS STEPHENSON (Marine Forensic Historian: It's almost like a C.S.I. situation, when you have a crime scene.

NARRATOR: Can forensic science unlock the secrets of the mystery sub and reveal the true story of the attack on Pearl Harbor?

DANIEL MARTINEZ (Historian, National Parks Service): Pearl Harbor is wrapped in enigma and mystery, and somewhere is the truth.

NARRATOR: Killer Subs in Pearl Harbor, next on NOVA.

NARRATOR: Oahu: One of the Hawaiian Islands; a vacation paradise in the Pacific; spectacular vistas, tropical beaches and vivid reminders of the past.

For a few hours, early on December 7th, 1941, this little piece of heaven became a living hell.

The sky, that Sunday morning, blazed in the crossfire of a fierce aerial assault: more than 350 Japanese aircraft bombing and blasting the American Pacific Fleet berthed in Pearl Harbor; dive-bombers strafing people, planes and structures on the shore.

The surprise attack shook not only the entire harbor, but also an entire nation that suddenly found itself at war. Over 2,400 Americans lost their lives in the battle. Almost half of them died on just one ship, the U.S.S. Arizona.

It remains under the sea, a powerful symbol of a devastating day.

Today a monument is built on top of the wreck. Over a million people visit each year and pay their respects to the 1,177 men, most of whom remain entombed inside the hull of the Arizona below, a sunken, 600-foot-long steel coffin.

Don Stratton was on the Arizona, directing anti-aircraft guns at incoming planes, when the ship caught fire and sank.

DONALD G. STRATTON (U.S.S. Arizona Survivor): My hair was burned off; I lost part of my nose, part of my ear; my back was burnt; both my legs are burnt. It was just a hell of a day, but I don't talk about it that much, so that's all I've got to say about that.

NARRATOR: But there was another part of the Japanese offensive completely hidden from view.

AKIRA IRIYE (Harvard University): ...popular perception is that the Pearl Harbor attack was primarily an aerial attack, coming from the sky.

EDWARD T. O'DONNELL (College of the Holy Cross): It's the ultimate air raid, but a closer look at the battle of Pearl Harbor really reveals that there's a lot more to it than that. It also tells us a lot about the Japanese expectations that they really wanted to completely cripple the Pacific Fleet.

NARRATOR: Compelling evidence now suggests that Pearl Harbor was attacked not only from above, but below.

Hours before Japanese aircraft carriers launched their planes from a position north of Oahu, a secret weapon was already approaching from the south.

According to military records, shortly after midnight, five Japanese submarines slipped undetected to within just a few miles of Pearl Harbor,

each one carrying a technological marvel on its back: a two-man midget sub.

The five Type A midget submarines were about a quarter the length of the mother sub. Just six feet wide and packed with equipment, these miniature subs were designed for efficiency, not comfort.

A 600-horsepower electric motor propelled the midget subs swiftly under water at 19 knots, twice as fast as many other World War II submarines. The midget subs could not only take the enemy by surprise, they could hit the enemy hard.

The bow of a midget sub on display at the Naval Academy in Japan shows how.

COMMANDER MASANORI ANDOU (Japan Maritime Self-Defense Force): It carried two Type 97 Long Lance torpedoes, specially made for this midget sub.

NARRATOR: Just one of these modified Long Lance torpedoes could punch a hole in a towering battleship.

The Japanese built hundreds of midget submarines during World War II and deployed them all across the Pacific and Indian Oceans.

The surprise attack on Pearl Harbor would be the midget sub's opening act for the war that followed.

Author Burl Burlingame has investigated their top-secret operation.

BURL BURLINGAME (Author, Advance Force-Pearl Harbor): The midget submarines were supposed to get in the harbor, lie low, wait for the attack to happen, and then surface, fire their torpedoes into the American ships, attacking them from the bottom as well as from the top.

NARRATOR: But how well did the plan succeed?

We know that four of the five midget subs launched that morning failed in their mission.

BURL BURLINGAME: One midget submarine was sunk before the attack. It did not fire its torpedoes.

NARRATOR: Midget sub number 1 was shelled by the U.S.S. Ward, over an hour before the Japanese warplanes attacked.

It remains where it sank, just outside the harbor.

Midget sub number 2 entered Pearl Harbor, but after missing its target with both torpedoes, the sub was destroyed by a pair of American ships. It was raised two weeks after the attack and buried as landfill.

Two down, and another two would never make it even close to the harbor.

Midget sub number 3 ran aground on the east side of Oahu,

and its captain became the first Japanese prisoner of war. Neither of its torpedoes had been fired.

It is now on display at the National Museum of the Pacific War, in Texas.

The fourth midget sub turned up years later, several miles south of Pearl Harbor.

BURL BURLINGAME: Another midget submarine was found in 1960, at Keehi Lagoon, and it still had its torpedoes in it.

That midget submarine was shipped back to Japan.

NARRATOR: It now stands outside the Naval Academy in Etajima.

EDWARD O'DONNELL: It's pretty clear that four of the submarines did not actually complete their mission.

NARRATOR: What about number 5, the last of the midget subs?

PARKS STEPHENSON: The fifth one was a mystery. Historians differed on what it could have done, or where it could've ended up.

NARRATOR: We know that midget sub number 5 began its journey in Kure, Japan. Petty Officer Kichiji Dewa was aboard its mother sub the night number 5 launched into battle. Dewa recorded his thoughts in a secret diary.

KICHIJI DEWA (Imperial Japanese Navy, Retired): After long days of waiting, X Day has come. The crew were dressed in clean clothes and prepared.

NARRATOR: During the war, the Japanese were told that the fifth midget sub had scored a devastating kill.

BURL BURLINGAME: The Japanese midget submariners became the heroes of the attack, in Japan. They were given credit for sinking the U.S.S. Arizona.

NARRATOR: Did midget sub number 5 sink the Arizona or any other American battleship that day in Pearl Harbor?

DANIEL MARTINEZ: I think that a cat and mouse game is still going on, with historians trying to find out what happened to the fifth sub.

NARRATOR: Now, after almost 70 years, the mystery may be solved and the true story of the attack on Pearl Harbor finally revealed.

Terry Kerby is a submersible pilot who has been exploring the ocean floor around the Hawaiian Islands for years. The area just outside of Pearl Harbor is an underwater museum of World War II debris.

TERRY KERBY (Director of Operations, National Oceanic and Atmospheric Administration/Hawaii Undersea Research Lab): We found wrecks of airplanes and vehicles and pier parts and lots of junk.

NARRATOR: During a routine test dive, three miles south of Pearl Harbor, Terry spotted something unusual.

TERRY KERBY: That's definitely a conning tower sticking up.

NARRATOR: It was a long tube of steel, and to an expert eye it resembled part of a Japanese midget sub.

Terry eventually found two more sections spread out across the ocean floor. But are all three pieces from the same submarine? And if so, is it the wreck of midget sub number 5, missing since December 7th, 1941?

NOVA has assembled a unique team of investigators to find out. They come from both sides of the battle: America and Japan.

Leading the investigation is marine forensic historian, Parks Stephenson, a former U.S. Navy officer and submariner.

PARKS STEPHENSON: Today's the day. After months of study, we are actually going down to the wreck of the midget sub that we've identified as potentially the last of the missing Japanese midget subs that participated in the attack on Pearl Harbor.

NARRATOR: Joining Parks is Admiral Kazuo Ueda.

PARKS STEPHENSON: I was honored that Admiral Ueda offered to come out here. He was the senior surviving midget submariner from the war. No one knows the whole context of the Japanese midget subs better than he.

NARRATOR: Admiral Ueda has his doubts about the midget sub.

He doesn't think it's midget sub number 5, but one damaged and dumped by American forces later in the war.

Historian Go Okumoto knows midget subs from the inside out.

PARKS STEPHENSON: He wrote a book on the midget submarines, he's probably the premier Japanese expert.

NARRATOR: Go wants to study the wreck before drawing any conclusions.

The Japanese built hundreds of midget subs during the war.

BURL BURLINGAME: One of the few things we know about the midget submarines as a class of submarines is that the, the Japanese navy was always tinkering with them.

NARRATOR: The five midget subs deployed at Pearl Harbor were early models and unlike any that followed.

The team plans to dive over a thousand feet below the surface in two deep-sea research submersibles, the Pisces IV and the Pisces V.

Admiral Ueda will dive in the Pisces IV.

Go joins Parks Stephenson in the Pisces V, with Terry Kerby at the controls.

Just big enough for a three-person crew, the submersibles can dive to a depth of over a mile and stay down for up to 10 hours.

Equipped with instruments to monitor the ocean and collect samples, the Pisces IV and the Pisces V are state-of-the-art midget submarines. But they're tools of science, not weapons of war, entirely different from the Japanese midget subs of 1941.

Even though Terry's been down here before, doesn't mean the sub is easy to find.

After searching for over an hour, the crew sees some World War II wreckage.

PARKS STEPHENSON: We have come across what appears to be an upside-down amphibious track vehicle. Looks like there's been damage to the underside of it.

NARRATOR: These are the wrecks of several amphibious assault vehicles, but nestled among them...

TERRY KERBY: Okay, we've got something coming up here.

NARRATOR: ...what, at first glance, could be a torpedo, is actually the stern of a Japanese midget submarine.

The size and shape are unmistakable to historian Go Okumoto. To learn more, he and Parks want to examine the rudder, the moveable fin that steers the sub.

PARKS STEPHENSON: We want to see the rudders. We're going to try and match the rudders to that single screw guard.

NARRATOR: The rudder design on the five subs sent to Pearl Harbor was never used again. That's because it was a liability.

MASANORI ANDOU: The rudder is very small in proportion to the body of the ship. This means that it is not very powerful. This makes it necessary for the sub to have a large turning radius.

NARRATOR: After Pearl Harbor, the Japanese would change the rudder design to make the midget subs more maneuverable.

The Pisces V moves in for a closer look.

TERRY KERBY: So this looks like it landed on its tail. It's kind of crumpled up a bit.

NARRATOR: Though the stern is badly damaged, the rudder on its back is still visible.

PARKS STEPHENSON: We still do see the small thin rudders. Based on that, again, this is consistent with a Pearl Harbor submarine.

NARRATOR: One piece of the puzzle may be in place, but a cable dangling from the stern doesn't quite fit.

PARKS STEPHENSON: What's that curved piece of metal over to the left? Is that a cable or...

TERRY KERBY: That's a cable.

NARRATOR: Go believes this cable is completely out of place and not part of any Pearl Harbor midget sub.

TERRY KERBY: Pisces IV, we're moving on.

MAX CREMER: Roger, go ahead.

NARRATOR: Terry Kerby steers the Pisces V toward the second piece of the wreck, as the Pisces IV follows.

Before the war, the American military knew almost nothing about these midget subs. They were the Japanese navy's most guarded secret weapon.

BURL BURLINGAME: We simply didn't know about these midget submarines. And when they appeared at Pearl Harbor, they actually caused quite a stir.

NARRATOR: The December 7th attack turned out to be not only a military surprise but also a technological one.

Other countries were developing midget subs, but they were mostly human-guided torpedoes; crude, unreliable and often suicide weapons.

PROFESSOR HARUO TOHMATSU (National Defense Academy of Japan): Technically speaking, the Japanese midget subs were far superior to their counterparts produced by British, German or Italian navies.

NARRATOR: The Japanese versions were more like real submarines, but much more compact.

BURL BURLINGAME: They were able to miniaturize the propulsion technology and use batteries.

NARRATOR: The midget sub made ingenious use of its limited space. Divided into seven compartments, both pilot and captain operated inside a control room the size of a closet, crammed with switches, instruments and a radio-telegraph.

These cleverly designed machines were constructed in a closely guarded plant, in three separate sections, almost the same way the mystery sub would be found decades later.

Terry Kerby maneuvers into position next to what appears to be the midsection of a Japanese midget sub.

KAZOU UEDA: It is much different than I expected. The sub is quite wrecked.

NARRATOR: Parks and Go are looking for a pulley.

The mouth of Pearl Harbor was protected by anti-torpedo nets, so the midget subs had net-cutters attached to the bow. A cable was installed, with a pulley, to guide the net up and over the sub so it wouldn't get caught.

At first they can't see it. Then...

TERRY KERBY: Alright, so there's the tensioning pulley.

NARRATOR: After Pearl Harbor, both pulley and cable were modified. According to historian Go Okumoto, this pulley looks like it belongs on a Pearl Harbor midget sub.

Yet with each new clue comes another puzzle.

They find a mysterious cable attached to the midsection, just like the one on the stern.

But there's still one more piece to examine.

TERRY KERBY: Roger, can you give us direction and range to the bow section? Over.

NARRATOR: The sharp-edged net-cutters attached to the bow of the five Pearl Harbor midget submarines were unique. Unlike any others that followed, they were shaped like a figure eight.

BURL BURLINGAME: After the Pearl Harbor attack, it was assumed that the midget submarines had trouble getting through our nets, so they added these great big net-cutters that looked like something out of a Jules Verne novel.

NARRATOR: The figure-eight net-cutter is key to identifying midget sub number 5.

TERRY KERBY: The current has put us into position.

NARRATOR: The Pisces submersibles move in on the bow.

PARKS STEPHENSON: There it is, right frickin' there.

NARRATOR: Admiral Ueda confirms the discovery.

ADMIRAL KAZUO UEDA (Japan Maritime Self-Defense Force): It is in the shape of a number eight. One can conclude definitely that this was the special submarine that was used in Pearl Harbor.

NARRATOR: Go Okumoto agrees.

GO OKUMOTO (Historian and Author): This is the last of the midget sub.

PARKS STEPHENSON: This is the last of the midget subs.

NARRATOR: Out of sight at the bottom of the sea for almost 70 years, midget sub number 5 has at last been found.

A giant piece of the Pearl Harbor puzzle has fallen into place.

And now, the key question can perhaps be answered. We know that none of the other midget subs successfully fired their torpedoes inside Pearl Harbor. But unlike the other four, did midget sub number 5 fire its torpedoes into a battleship?

HARUO TOHMATSU: The navy high command actually believed that it heavily damaged or sunk one American battleship at Pearl Harbor.

NARRATOR: Japanese war records reveal that shortly after midnight on December 7, 1941, midget sub number 5 surfaced seven miles outside of Pearl Harbor on the back of its mother sub.

As the mother sub slowly descended for the launch, the two-man crew of number 5 was ready for action.

Pilot Sadamu Kamita sent a final letter to his parents: "Should anything happen to me, do not grieve, for I have dedicated my life in service to His Imperial Majesty."

Years earlier, Commander Masaji Yokoyama had written four words on his naval academy notebook, "vigor, spirit, patience" and "honesty." Both men would need these attributes in the hours ahead.

Petty Officer Kichiji Dewa recalls that Kamita and Yokoyama were highly qualified for the job.

KICHIJI DEWA: They were specially selected who proved to be at the top of their class.

We were more than brothers. Especially, for midget submarines, it is something that deals with life and death.

NARRATOR: Dewa was the last person to speak with the crew.

KICHIJI DEWA: Before going off to attack, the captain of the midget submarine said, "Thank you for your maintenance work." The only response I could give him was, "Please take care, and good luck."

NARRATOR: With that, the two submarines pulled apart. The mother sub remained at sea, while number 5 headed straight for the mouth of Pearl Harbor.

But did it do any harm?

The camera on Pisces V is able to peer right inside the torpedo tubes. Both of them are empty.

PARKS STEPHENSON: We're right at the business end of the bow section of the midget submarine, staring right down the empty torpedo tubes. It's an amazing sight.

NARRATOR: But if midget sub number 5 succeeded in firing its torpedoes, did they find their target?

Around 10:40 p.m., some 12 hours after the attack, Petty Officer Dewa received a message in Morse code from midget sub number 5: the Japanese characters "ki ra," a message that made no sense. Dewa thinks the exhausted crew made a mistake.

KICHIJI DEWA: Yokoyama's sub wanted to send the signal "tora," but I think they mistakenly sent "ki ra" instead.

NARRATOR: "Tora" begins with a dot, dot. "Ki Ra" begins with a dash, dot. All it takes is an extra second on the clicker to turn a dot into a dash.

KICHIJI DEWA: Their hand might have slipped.

NARRATOR: Tora was a Japanese code word.

KICHIJI DEWA: The airplanes that flew to Hawaii sent the same signal "Tora, tora, tora."

NARRATOR: It meant, "We have succeeded in our surprise attack."

The mother sub sent word to the Japanese high command, where the report of success was taken as fact. In their absence, the midget submariners were accorded the highest honors.

HARUO TOHMATSU: During the war time, these midget sub crews were regarded as hero gods.

BURL BURLINGAME: ...which is sort of like in between human and God. And they, they sold posters of them. They were sort of like the rock stars of, of World War II Japan.

DANIEL MARTINEZ: The Japanese media embraced the idea that these men had sacrificed everything for the nation, made a film about them.

BURL BURLINGAME: They had books written about them. The midget submariners were given vast amounts of, of credit for, for the success of the attack.

NARRATOR: And for Petty Officer Dewa, who had come to know the crew of number 5, the message had a special meaning.

KICHIJI DEWA: "They did it!" That's what I felt. We were eagerly waiting for the news of success. When we finally received it, I realized our success.

NARRATOR: The two empty torpedo tubes appear to support that success.

But just because the tubes are empty doesn't mean the torpedoes were fired. Perhaps they were removed?

The answer to this question cannot be found below.

DANIEL MARTINEZ: Pisces V KoK, you are clear to surface, clear for surface, over.

PARKS STEPHENSON: Definitely a Pearl Harbor sub, the empty torpedo tubes just really stand out.

NARRATOR: Forensic historian Parks Stephenson wants to discover exactly what those empty torpedo tubes mean.

He sends all the information to microbial ecologist Lori Johnston, an expert in what happens to metals under water.

Even though the encrustation on the torpedo tubes looks like rust, it's not. Ordinary rust is a purely chemical reaction. This is something entirely different, known as a "rusticle."

LORI JOHNSTON: A rusticle is a living organism. It's actually bacteria, micro-organisms that are naturally found in the environment.

NARRATOR: Also found on the wreck of the Titanic, rusticles feed on metal in salt water.

LORI JOHNSTON: This is an example of a rusticle. It's full of little crevices and cracks and tunnels. You're not dealing with one type of bacteria, you're dealing with multiple types of bacteria: a "consorm," or a consortium of bacteria.

Each different tunnel has different types of bacteria working together. That's why they are so good at being able to break down steel. Any types of metal, any types of nutrients, they're able to incorporate that within the rusticle structure.

NARRATOR: Bacteria most likely would have started breaking down midget sub number 5 soon after it sank.

LORI JOHNSTON: Once the sub has been in the water for a very short period of time, within weeks and months, encrustation has already started to form.

So it's almost like cementing the torpedo within the tube.

NARRATOR: That would make it extremely dangerous to remove.

LORI JOHNSTON: It would be taking your life in your own hands by removing an active, a live torpedo that had started to cement in the tube.

NARRATOR: Lori believes all the evidence points in a single direction.

LORI JOHNSTON: It's my conclusion that—after analyzing the data—that this sub fired its torpedoes prior to its sinking.

NARRATOR: If midget sub number 5 fired both of its powerful Long Lance torpedoes, what was the target?

Just 40 feet beneath the surface of Pearl Harbor lays the wreck of the U.S.S. Arizona, where over a thousand American servicemen lost their lives, and where most of them still remain.

Diver John Chatterton and National Parks Service archaeologist Matt Russell will search for evidence of a torpedo hit on the hull of the Arizona.

It's a war grave.

Only a select few are permitted to dive here, and even fewer are allowed to film what lies at rest beneath the waves.

As Chatterton and Russell explore the wreck, the events of the day come alive.

JOHN CHATTERTON: This is a stairway. On December 7th, 1941, American sailors would have been running up these steps, grabbing onto these handrails and trying to save their ship.

MATT RUSSELL (U.S. National Park Service): This is the original wood planking that covered the main deck of Arizona back here in the stern.

JOHN CHATTERTON: This looks like scarring from shrapnel over here and, and over there.

MATT RUSSELL: It could be battle damage from the December 7th attack.

NARRATOR: We know that the Arizona was attacked by bombs from above, but some eyewitnesses say it was also torpedoed from below.

Arnold Bauer was aboard the U.S.S. Vestal, a repair ship, moored alongside the Arizona.

PARKS STEPHENSON: So you are 100 percent confident that the Arizona received one or more torpedoes during the attack.

ARNOLD BAUER (U.S.S. Vestal Survivor): Yup, I saw the track.

PARKS STEPHENSON: Okay, so you were standing here, on the quarterdeck.

ARNOLD BAUER: And I went over on this side to see what was going to happen to this side.

PARKS STEPHENSON: Why did you go running over here?

ARNOLD BAUER: Because I figured if a torpedo was going to hit here, I wanted to be on the other side.

NARRATOR: On the morning of December 7th, 1941, Don Stratton was defending the Arizona from incoming fire, and he remembers a pair of torpedoes heading towards the ship.

DON STRATTON: I swear, to this day, that two of them were headed right toward the Arizona and the Vestal.

PARKS STEPHENSON: For those people who say that the Arizona definitely wasn't torpedoed, what do you have to say to them?

DON STRATTON: They weren't there.

PARKS STEPHENSON: But you saw them.

DON STRATTON: I saw them, for sure.

NARRATOR: But after hours of searching, Matt Russell and John Chatterton can't find any evidence of a torpedo hit.

JOHN CHATTERTON: We've gone over virtually every inch of the port side of Arizona's bow. We don't see anything that would indicate damage from a torpedo.

NARRATOR: But what if that torpedo was a dud?

Anti-submarine expert Tom Taylor has uncovered an obscure passage in a Congressional report by Admiral Nimitz, Commander of the Pacific Fleet.

It describes an unexploded torpedo sighted inside Pearl Harbor, one that may have come from midget sub number 5.

TOM TAYLOR (United States Navy, Retired): At the end of one of the paragraphs, it states a recovered, unexploded torpedo carried an explosive charge of 1,000 pounds.

We knew that the aerial torpedoes were only around 500 pounds.

PARKS STEPHENSON: That could only be a submarine torpedo. The aerial torpedoes were less than half that charge.

TOM TAYLOR: The fact that he reported that they recovered this torpedo indicates corroborating evidence that a midget sub had penetrated Battleship Row and had fired upon it.

NARRATOR: We will never know if that torpedo was intended for the U.S.S. Arizona, but if it was a dud, that still leaves one more torpedo unaccounted for. On the morning of the attack, the U.S.S. West Virginia and the U.S.S. Oklahoma were forward of the Arizona on Battleship Row.

Two naval experts believe they have found a photograph of midget sub number 5 in action against at least one of them.

Recovered after the war, this picture was taken by a camera on a Japanese plane the morning of December 7th.

It's fuzzy and unclear, but some experts believe it's a midget sub firing a torpedo straight into Battleship Row.

Naval intelligence officer John Rodgaard and forensic engineer Peter K. Hsu have spent years analyzing this single photograph.

CAPTAIN JOHN RODGAARD (United States Navy): What we see in this photo is the effects of the initial aerial torpedo strikes against Battleship Row.

We can see the concussion waves radiating out from the ships that have been hit. We can see torpedo tracks in the water. We see an object in the water with a distinctive horizontal feature and a distinctive vertical feature.

NARRATOR: Both are features of a midget submarine.

JOHN RODGAARD: The vertical feature would be the sail, the horizontal feature, the hull. We can see behind it, plumes of water caused by a propeller.

PARKS STEPHENSON: Could those plumes of water be caused by a torpedo being dropped by an airplane?

JOHN RODGAARD: No because a torpedo hitting the water has a distinctive splash. It is a forward movement. This does not have that characteristic. It is more of a fountain effect, caused by a propeller.

NARRATOR: The propeller of midget sub number 5.

Whenever a Japanese midget sub fires a torpedo, there's a sudden loss of balance.

MASANORI ANDO: A torpedo weighs about one ton; the sub weighs 46 tons. When a torpedo is launched, the forward part suddenly gets one ton lighter.

NARRATOR: ...which, in turn, rocks the sub up and down as the crew struggles to regain control.

This creates a unique plume of water called a rooster tail, which occurs when the propeller flies out of the water.

But did the torpedo hit its target?

The rooster tails in the photograph could offer a clue.

According to Hsu, an expert in fluid dynamics, one of these rooster tails may also be the result of the midget sub torpedo hitting its mark.

Under John and Peter's guidance, NOVA has taken the team's original classified calculations and re-engineered them into revealing animation.

When a torpedo blasts into a ship, it produces a shockwave powerful enough to lift a sub out of the sea, even at a distance. The shockwave created by an airborne torpedo isn't powerful enough to reach the midget sub.

PETER HSU (Forensic Engineer, United States Navy): The area generated by the shockwave does not reach the submarine.

NARRATOR: Because a torpedo fired by a midget sub has a warhead almost twice the size as an airborne one, the shockwave it creates radiates much farther.

And when that torpedo hits its target...

JOHN RODGAARD: Cavitation extends beyond the submarine and lifts it above the surface.

NARRATOR: But how does the animation compare with the original photograph?

JOHN RODGAARD: What we see in the animation is the effect of the explosion on both the submarine and the large rooster tail—as we can see—as a snapshot in time of the large plume behind the submarine, in the photograph, and the plume rising alongside the West Virginia, and the correlation is perfect.

NARRATOR: The West Virginia took at least seven torpedo hits.

The Oklahoma was hit by up to nine torpedoes.

While most were launched from planes, Rodgaard and Hsu believe that two of those torpedoes were fired by midget sub number 5.

JOHN RODGAARD: striking the West Virginia, the other one appearing to move towards the Oklahoma.

NARRATOR: This leaves us with conflicting conclusions. If the accounts of some eyewitnesses and the Nimitz report are to be believed, one torpedo was fired at the Arizona but turned out to be a dud.

If the photographic experts are to be believed, then two torpedoes were fired, hitting the West Virginia and the Oklahoma. Either way it appears likely that midget sub number 5 successfully fired its torpedoes inside Pearl Harbor.

So after completing its mission where did it go?

DANIEL MARTINEZ: We actively know, through documents and through primary source photographs, that there was a hunt for these submarines. The chances of one getting out, I think, is extremely narrow.

NARRATOR: During the attack, a U.S. naval minesweeper reported both sighting and firing upon what appeared to be a midget submarine trying to escape the harbor.

KICHIJI DEWA: They had nautical charts of Hawaii in their hand; they had the basic map of inner harbor memorized in their head.

DANIEL MARTINEZ: Where would the sub go? What was safe?

NARRATOR: Parks Stephenson examines a Japanese map from one of the recovered midget subs.

PARKS STEPHENSON: So, if I'm looking at this chart, and I seem to be running out of options, there's this area here which is open and, according to this Japanese legend over here on the side, the West Loch doesn't have a whole lot in it.

NARRATOR: Parks believes number 5 escaped to the relative isolation of the West Loch, at the time, a backwater fueling area.

But what happened to the sub and its crew, Commander Masaji Yokoyama and Pilot Sadamu Kamita?

During the investigation of the wreck, the team discovered what could be a frightening clue.

About 10 feet of the sub appears to be missing.

PARKS STEPHENSON: If you look at the edges of this torn steel here, it's bent outward. Whatever did the damage back here came from inside the sub.

NARRATOR: In order to keep Japan's secret weapon out of enemy hands the crew was instructed to escape if they could, but to destroy their submarine by igniting a scuttling charge lashed to the midsection.

Did Yokoyama and Kamita follow these instructions? And if so, how?

NOVA has recruited a team of experts to find out. If the two men scuttled their sub on the surface, they could have lit the fuse and possibly escaped with their lives. If the crew was submerged, then the crew is probably still sealed inside.

Naval Engineer Roger Long has created a scale model of a midget submarine from an old scuba tank.

Demolitions expert David Loring is in charge of the action.

DAVID LORING (Demolitions Expert, United States Navy): This is Naval Weapons Station Earle E.O.D. demolition range, about 11,000 acres of bombs and bullets.

ROGER LONG(Engineer, United States Navy): And we're going to test it on the surface, with this open, as if they set off the scuttling charge floating, and then we're going to explode under water with a plastic cap to simulate the fact that the hatch only has a very small resistance to blowing open. And we'll be looking for differences in the damage patterns between the surface submarine and the sunken submarine.

DAVID LORING: We're going to be utilizing underwater explosive, C4. We're going to place it inside the sub, in the approximate location that the scuttling charges are placed, which is in this area here.

NARRATOR: The first experiment will replicate a scuttling charge with the midget sub surfaced.

BRIAN HOPKINS (United States Navy): Fire in the hole! Fire in the hole! Fire in the hole!

NARRATOR: The first result is disappointing. It doesn't match the damage discovered under water.

ROGER LONG: It doesn't look anything like the one we're thinking about.

NARRATOR: The team decides to experiment with a slightly larger charge.

BRIAN HOPKINS: Fire in the hole!

PARKS STEPHENSON: We're going to need another tank.

NARRATOR: Whether the charge is large or small, it appears that midget sub number 5 was not scuttled on the surface.

A new tank is prepared, and the replica of the midget sub is secured to the bottom.

ROGER LONG: Next, we want to replicate the other surface model with a smaller charge—exactly the same charge, but at the bottom of that tank over there, so we can see what happened if it exploded on the bottom.

BRIAN HOPKINS: Fire in the hole!

ROGER LONG: The damage is a lot more similar to the Pearl Harbor sub, which leads me to think that the scuttling charge was set off with the sub on the bottom, not on the surface.

NARRATOR: The demolition team concludes that the sub was scuttled under water, which implies the remains of the crew are still inside.

But none of this explains how midget sub number 5 wound up in three pieces, at the bottom of the ocean, several miles outside Pearl Harbor.

During the underwater investigation, three mysterious cables were found attached to all three pieces of the submarine.

For a salvage diver like John Chatterton, this can only mean one thing.

JOHN CHATTERTON: My best guess is that this submarine was salvaged, it was brought up, put on some kind of platform. It was cut apart. The three sections were taken apart, and then they were taken out and dumped.

NARRATOR: But who dumped it and why?

John Chatterton joins Parks Stephenson for a closer look at the West Loch, where the team believes midget sub number 5 was scuttled.

JOHN CHATTERTON: What do we have over here, Parks?

PARKS STEPHENSON: Well this is the Waipio Peninsula, its largely un-inhabited peninsula, part of the naval reservation. Back in 1941, it was covered with sugar cane fields. But this is the entrance to the West Loch.

NARRATOR: And then they see it, the final clue, hidden in plain sight.

PARKS STEPHENSON: Now, what we're approaching here is the wreck of the L.S.T. 480.

NARRATOR: An L.S.T. It stands for Landing Ship, Tank.

These are naval vessels built to carry troops, cargo and tanks directly onto shore.

The area surrounding the wreck of midget sub number 5 is littered with the landing craft the L.S.T.s carried.

TERRY KERBY: That's a big rock here. Oh, no, it's not a rock, it's a landing craft.

PARKS STEPHENSON: When we were searching for the midget sub pieces, we ran across numerous damaged amphibious track vehicles.

TERRY KERBY: Oh, no, this is another landing craft, a different one. Ah, they're all over the place.

NARRATOR: But why are they here?

Turns out Pearl Harbor suffered more than one unexpected disaster on a Sunday morning. It took place three years later, on May 21st, 1944.

Unlike December 7th, this second disaster is not well known, because, until recently, it was veiled in secrecy. As the Navy prepared for the invasion of the Pacific island of Saipan, a terrible explosion claimed the lives of almost 200 people in the West Loch.

PARKS STEPHENSON: There was an accident in the ammunition handling being loaded aboard the L.S.T. 353. The explosion spread from L.S.T. to L.S.T., sank six L.S.T.s, killed a couple hundred sailors, wounded hundreds more.

NARRATOR: The invasion needed to get back on track, so the West Loch was cleaned up quickly and quietly. The remnants of the disaster that could be raised were hauled outside the harbor and dumped.

But along with the damaged equipment, it appears the Navy may have also scooped up midget sub number 5, long after it was scuttled in the West Loch.

PARKS STEPHENSON: It's my contention that during that clean up, they found our midget sub. They raised it, they put it in with the rest of the debris and took it out there and dumped it all together.

NARRATOR: Perhaps that's why it now lies amidst an assortment of U.S. military hardware from the West Loch disaster, three miles outside Pearl Harbor, a thousand feet at the bottom of the sea.

Today Admiral Ueda visits the wreck of midget sub number 5 to honor the remains of pilot Sadamu Kamita and commander Masaji Yokoyama.

KAZUO UEDA: Mr. Kamita, here is your brother. Here is Mr. Dewa who accompanied you to Pearl Harbor.

NARRATOR: A cup full of sand is carefully removed from the seafloor, beneath the sealed control room of the midget sub, and given to Admiral Ueda to take home.

AKIRA IRIYE: The remains or the spirits of the dead, ah, from the submarine would now be reunited with the sand.

NARRATOR: Admiral Ueda presents the sand to Petty Officer Dewa.

He brings it to a memorial service for Japanese sailors who lost their lives in midget submarines.

AKIRA IRIYE: The sand that was brought back from Hawaii is purified now, becomes Japanese soil, so to speak.

NARRATOR: For Kichiji Dewa, the mission is at last over. For Parks Stephenson, it's always been about bringing the facts to light.

PARKS STEPHENSON: I want their accomplishment known, so that their sacrifice will have meaning.

NARRATOR: Time may yet uncover new details in the history of Pearl Harbor. And each step we take towards the truth of the heroic and tragic events of that day, not only honors the people who lived it, but serves future generations, as the real story is finally revealed.

Broadcast Credits

Killer Subs in Pearl Harbor

Produced and Directed by
Kirk Wolfinger
Written by
Steven Reich
Produced by
Lisa Quijano Wolfinger
Steven Reich
Edited by
Ryan Shepheard
Supervising Producer
Rocky Collins
Associate Producer and Additional Directing
Sally Levi
Underwater Camera
Brett Seymour
Joseph Brunette
Yoram Astrakhan
Paul Atkins
Sean Glenn
John Mans
Sound Recordists
Pete Nenortas
Kristopher Dennett
Gracie Atkins
Tom Eichler
Edward Thacker
Narrated by
Jay O. Sanders
Hans Indigo Spencer
Additional Editing
Jed Rauscher
Production Manager
Donna Huttemann
Rushmore DeNooyer
Post Department
Jared Flynn
Corey Norman
Mike Olcott
Nate Lavey
Tracy Bisson
Adam Farris
Business Manager
Chris Bailey
Executive Producer for Lone Wolf Documentary Group
Kirk Wolfinger
Online Editor and Colorist
Michael H. Amundson
Audio Mix
Greg McCleary
Sound Design
Geof Thurber
Archival Material
WWII: Valor in the Pacific National Monument, Photo Archive
Japanese Midget Submarine Association
The National Archives
National Park Service
Hawaii Undersea Research Laboratory, University of Hawaii
U.S. Navy — Submarine Force Museum
UCLA Film & Television Archive
Special Thanks
"Advance Force — Pearl Harbor" by Burl Burlingame, Pacific Monograph
The Army and Navy Club, Washington, DC
Battleship USS Missouri, Pearl Harbor, HI
Earle Naval Weapons Station
Fox Glass
JMSDF 1st Service School Eta Jima
Carroll Lucas (dec.)
Larry Murphy
National Museum of the Pacific War
Naval History & Heritage Command, Washington Navy Yard
Navy Region Hawaii
New Mexico Tech
Brett Seymour
Specialty Diving Services, YT-153
United States Navy
Yamato Museum
The Washington Navy Yard
Midori Yanagihara
Special Thanks to the USS Midway Museum, San Diego, California
NOVA Series Graphics
yU + co.
NOVA Theme Music
Walter Werzowa
John Luker
Musikvergnuegen, Inc.
Additional NOVA Theme Music
Ray Loring
Rob Morsberger
Closed Captioning
The Caption Center
NOVA Administrator
Mykim Dang
Carole McFall
Eileen Campion
Victoria Louie
Karinna Sjo-Gaber
Karen Laverty
Steve Sears
Kate Becker
Senior Researcher
Gaia Remerowski
Production Coordinator
Linda Callahan
Sarah Erlandson
Talent Relations
Scott Kardel, Esq.
Janice Flood
Legal Counsel
Susan Rosen
Production Assistant
Ryan Murdock
Post Production Assistant
Darcy Forlenza
Associate Producer, Post Production
Patrick Carey
Post Production Supervisor
Regina O'Toole
Post Production Editors
Rebecca Nieto
Jason York
Post Production Manager
Nathan Gunner
Compliance Manager
Linzy Emery
Development Producer
Pamela Rosenstein
Supervising Producer
Stephen Sweigart
Business Manager
Joseph P. Tracy
Senior Producer and Project Director
Lisa Mirowitz
Coordinating Producer
Laurie Cahalane
Senior Science Editor
Evan Hadingham
Senior Series Producer
Melanie Wallace
Managing Director
Alan Ritsko
Senior Executive Producer
Paula S. Apsell

A NOVA Production by Lone Wolf Documentary Group for WGBH/Boston in association with NHK and Channel 4

© 2010 WGBH Educational Foundation All Rights Reserved

Image credit: (composite image) © WGBH Educational Foundation


Masanori Andou
Japan Maritime Self-Defense Force
Arnold Bauer
USS Vestal Survivor
Burl Burlingame
Author, Advance Force - Pearl Harbor
John Chatterton
Wreck Diving Expert
Kichiji Dewa
Imperial Japanese Navy (Retired)
Peter Hsu
Naval Architect/Forensic Engineer
Akira Iriye
Harvard University
Lori Johnston
Microbial Ecologist
Terry Kerby
Director of Operations, NOAA/HURL
Roger Long
Naval Engineer/Marine Investigator
David Loring
United States Navy, EOD (Retired)
Daniel Martinez
Historian, National Park Service
Edward O'Donnell
College of the Holy Cross
Go Okumoto
Author, The Entire History of Midget Submarines
John Rodgaard
United States Navy
Parks Stephenson
Marine Forensic Historian
Donald Stratton
USS Arizona Survivor
Tom Taylor
Anti-Submarine Ops, USN (Retired)
Haruo Tohmatsu
National Defense Academy of Japan
Kazuo Ueda
Japan Maritime Self-Defense Force (Retired)


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