Japan’s Midget Submarine Attack on Pearl Harbor Was a Suicide Mission
Nearly everything that could go wrong did for Japan’s submariners
by SÉBASTIEN ROBLIN
On Dec. 7, 1941, the aircraft of the Imperial Japanese Navy rained devastation upon the U.S. naval base at Pearl Harbor, Hawaii. But Japanese warplanes didn’t actually fire the first shots that brought America into a massive Pacific War.
An hour before the air attack, a squadron of tiny Japanese midget submarines attempted to slip into the harbor’s defenses, like burglars in the night, to wreak havoc on Battleship Row. Unlike the aerial assault, the sailors failed spectacularly — and the story is often forgotten.
By the 1930s, Imperial Japan and the United States were set on a collision course. Tokyo’s decision to invade China in 1931 and intensify its brutal campaign six years had provoked ultimately irrevocable tensions.
The United States responded to the incursion into China with increasing sanctions, culminating with an embargo on petroleum in July 1941 that crippled Japan’s economy. Japanese military leaders had wanted to capture the Dutch East Indies to secure its oil wealth, but knew it would trigger war with the Unites States.
While U.S.-Japanese negotiations came within striking distance of a peace agreement, Roosevelt was a hard bargainer, demanding Japan’s leaders order a complete withdrawal from China. They refused.
Thus, Japanese Adm. Yamamoto began planning for a “short victorious war.” The key to this idea was knocking out the battleships of the U.S. Pacific fleet at their home base of Pearl Harbor, Hawaii to buy the Japanese Army time to complete the conquest of the Western Pacific.
Althought a massive air strike from a Japanese carrier task force would constitute the main attack, the Navy coordinated the undersea assault using midget submarines.
During World War II, Japan, England, Italy and Germany all employed midget submarines to stealthily infiltrate shallow, defended harbors and attack vulnerable capital ships. The Japanese Navy’s midget submarines had hidden their developments by calling the ships Type A Kō-hyōteki , or “Target A”
Japanese officials hoped the designation would deceive foreign analysts into believing the 78-feet long submarines were actually mock ships for naval gunnery practice. In reality, each of the 46-ton subs had a crew of two and was armed with two 450-millimeter Type 97 torpedoes with 800 pound warheads.
The little submarines could sprint up to 26 miles per hour submerged, but could not dive deeper than 100 meters. More importantly, the Type As had no engine and ran purely on batteries.
This gave the diminutive vessels a maximum endurance of 12 hours at speeds of 6 miles per hour. The subs often ran out of power much faster in real combat.
As a result, a larger submarine mothership had to bring the Type As close to the target area. Even so, the battery limitations made it unlikely the midget sub could make it back to safety. Each one had a 300-pound scuttling charge as a self-destruct device.
Just getting to the target area was difficult enough. Since the small boats were difficult to control even while swimming in a straight line, crews had to manually move lead weights backwards and forwards to stabilize the vessel.
With these obvious issues, on Oct. 19, 1941, the Japanese Navy began modifying five Type A subs with improved pneumatic steering devices, as well as net-cutters and guards for fending off anti-submarine nets. Workers at the Kure Naval District painted over the submarine’s running lights to help hide them from enemy spotters.
Afterwards the midgets went to the Kamegakubi Naval Proving Ground and crews loaded them onto the backs of five large Type C-1 submarines, the I-16, I-18, I-20, I-22 and I-24. On Nov. 25, 1941, The motherships set sail for Pearl Harbor.
While on route, the so-called “Special Attack Unit” received the coded message “Climb Mount Niitaka 1208.” This meant authorities in Tokyo had not found a diplomatic solution and signaled the go-ahead for the Pearl Harbor attack.
On Dec. 6, 1941, the C-1s swam to points within 12 miles of Pearl Harbor. Then, between the hours of midnight and 3:30 A.M. the next day, the ships released their deadly payloads.
For the crews, getting inside Pearl Harbor posed a serious challenge. Ships could only enter the port through a 65 foot-deep channel guarded by an anti-submarine net 35 feet deep.
Boats on either side of the nets tugged them apart to allow friendly boats to pass through. On top of that, American destroyers prowled in a five mile arc around the harbor entrance, assisted by watchful eyes on orbiting PBY Catalina maritime patrol planes.
On paper, the Japanese intended for the submarine attack to work like a well-planned heist. The midget subs would sneak in by following American ships passing through openings in the anti-submarine net.
Then the subs would lay low until the air attack sowed chaos throughout the harbor, at which point they would unleash their torpedoes at any American battleships that survived the bombing. Afterwards, the midget subs would slip away to Hawaii’s Lanai Island.
The submarines I-68 and I-69 would wait no more than 24 hours to pick up any surviving crew. The Japanese did not plan to recover the Type As themselves.
If everything worked out right, American officials would only receive the Japanese declaration of hostilities mere moments before the attack commenced. However, things didn’t go according to plan.
Just before 4:00 A.M., the minesweeper USS Condor spotted the periscope of the midget submarine Ha-20 and called over the destroyer USS Ward to search the area.
Just over an hour and a half later, crew aboard the Ward spotted a periscope in the wake of the cargo ship Antares as it passed through the anti-submarines nets. While a PBY Catalina patrol plane dropped smoke markers near the sub’s position, the Ward charged the sub.
Gunners fired two shots from the ship’s 4-inch main gun at less than 100 meters and followed up with four depth charges. The Type A vanished into the water.
Depending on if you taking into account American actions in the Atlantic while the country was still technically neutral, these were the first shots fired in anger by U.S. forces in World War II. In 2002, a research submersible located the remains of Ha-20 and found Ward’s shells had struck the conning tower, killing the crew.
As the destroyer USS Monaghan joined Ward in searching for additional subs, the first of a total of 353 Japanese warplanes began their attack. Torpedoes slammed into the battleships sitting motionless at their docks while armor-piercing bombs plunged through deck armor.
By then, Japanese Navy Lt. Iwasa Naoji and the Ha-22 had made it inside Pearl Harbor and launched its first torpedo at the seaplane tender USS Curtiss. The projectile missed the mark, blowing up the dock behind the American ship.
Curtiss and the nearby tender USS Tangier returned fire with their 5-inch main guns, scoring at least one direct hit. From the decks, U.S. sailors raked the sub’s hull with .50 caliber machineguns.
At 8:45 A.M., the Monaghan’s captain sighted the sub as well and gave the order to ram it. Instead of fleeing, the iron-nerved Iwasa swung his sub around and fired his remaining torpedo at the charging destroyer — and missed by just 20 yards, passing parallel to Monaghan’s hull.
The destroyer slammed into the now unarmed submarine and unloaded depth charges for a good measure. The back blast from the depth charges thrust the destroyer’s bow out of the water and propelled it out of control into a collision with a nearby derrick.
But Ha-22 was done for.
Meanwhile, Japanese Navy Ensign Kazuo Sakamaki and Chief Warrant Officer Kiryoshi Inagaki had piloted Ha-19 right into trouble. Suffering from a broken compass, the two sailors repeatedly struck the coral reefs surrounding Pearl Harbor and eventually grounded the ship on the entrance to the bay.
A quarter-hour later the destroyer USS Helm spotted the Type A and opened fire — inadvertently blasting the sub free from the reef. The unfortunate sub managed to dodge a second attack from the American ship before grounding itself two more times on the reefs.
Taking on sea water caused the batteries to spew out deadly chlorine gas. A depth charge attack finally knocked out the periscope and disabled the midget submarine’s remaining undamaged torpedo.
Sakamaki decided to try and sail their stricken craft back to the mothership. He and Inagaki passed out as the choking gasses filling the inside of their ship.
The two managed to regain consciousness in the evening and decided to ground their sub near the town of Waimānalo to the east. However, they crashed on yet another reef.
A patrolling PBY bomber dropped depth charges on the crippled submarine. Sakamaki decided to abandon ship and attempted to detonate the scuttling charge — but even the ship’s self-destruct device failed to work.
Sakamaki succeeded in swimming ashore and promptly fell unconscious. His crewmate drowned.
The following morning, Hawaiian soldier David Akui captured the Japanese sailor. The first Japanese prisoner of war of World War II, Sakamaki refused to cooperate during his interrogation, requesting that he be executed or allowed to commit suicide.
The Japanese military became aware of his capture, but officially claimed that all of the submarine crews had been lost in action. A memorial to the Special Attack Unit omitted his name.
The crew of Ha-18 abandoned ship without firing either of their torpedoes after falling victim to a depth charge attack. Nineteen years later, the U.S. Navy recovered the sub from the floor of Hawaii’s Keehi Lagoon and ultimately shipped it off for display at the Japanese Naval Academy at Etajima.
The fate of the fifth submarine, Ha-16, remains controversial. At 10:40 P.M., the crew of the I-16 intercepted a radio message that appeared to repeat the word “Success!” A few hours later, they received a second transmission: “Unable to navigate.”
The belief was that Ha-16 transmitted these alerts. In 2009, a Nova documentary crew identified three parts of the midget submarine in a navy salvage pile off of West Loch, Hawaii.
A popular belief is that Ha-16 successfully entered the harbor and fired off its torpedoes. Then the crew slipped out and scuttled the sub off of West Loch island before perishing of unknown causes.
U.S. Navy salvage teams probably later scooped up the sub amidst the wreckage of six landing craft destroyed in the West Loch disaster of 1944. They then proceeded to dump the whole pile of debris further out at sea.
That no one ever found the Ha-16’s torpedoes gave rise to the theory that the midget submarine might have successfully torpedoed the battleship USS Oklahoma. The USS West Virginia was another possible target.
A photo taken from an attacking Japanese torpedo bomber at 8:00 A.M., which appears to show torpedo trails lancing towards Oklahoma without a corresponding splash from an air-dropped weapon added more weight to the idea. In addition, the damage to the Oklahoma, and the fact that it capsized, suggested to some it was struck by a tiny sub’s heavier torpedoes.
However, this theory is dubious. The Oklahoma capsized because all the hatches were open for an inspection at the time of the attack. The heavy damage can be explained by the more than a half-dozen air-dropped torpedoes that hit the ship.
It is more likely Ha-16 launched the torpedoes at another vessel. At 10:04 A.M., the light cruiser USS St. Louis reported it had taken fire from submarine, but both torpedoes missed.
In the end, the air attack accomplished what the midget submarines could not. Japan’s naval aviators sank three U.S. battleships, crippling another five, blasted 188 U.S. warplanes — most sitting on the ground — and killed 2,403 Americans, including service members and civilians.
Unfortunately for officials in Tokyo, the Japanese Navy had struck a powerful blow, but not a crippling one. The bombardment failed to hit the repair facilities and fuel depots, which allowed the U.S. Pacific fleet to get back on its feet relatively quickly.
Just as importantly, not a single U.S. aircraft carrier was in Pearl Harbor at the time. The flattops would swiftly prove their dominance over battleships in the coming Pacific War.
Despite the debacle, the Japanese Navy continued sending Kō-hyōteki into combat. As at Pearl Harbor, the submariners in their tiny ships had very limited successes in operations from Australia to Alaska to Madagascar.
War World II’s Pacific theater consumed many of the survivors of the Pearl Harbor attack. The Japanese lost all five of the Japanese Type C submarines that transported the Special Attack Unit in action. The destroyer Ward, which fired the first American shot of World War II, sank in December 1944 after kamikaze attack off of Leyte Gulf in The Philippines.
The same month, the destroyer Monaghan capsized in the devastating Typhoon Cobra in the Philippine Sea. All but six sailors died.
David Akui, who captured of the first Japanese POW, went on to serve with Merill’s Marauders in Burma, a storied U.S. Army unit that eventually lent its history to the famous 75th Ranger Regiment. He survived the war.
So did Kazuo Sakamaki. Despite suffering from both his own guilt over his capture and an at times hostile reception in Japan after the war, he went onto become an executive for Toyota and eventually wrote the memoir I Attacked Pearl Harbor.
As for Ha-19, the U.S. military grabbed the wreck during World War II and took it on a drive across the United States to encourage Americans to buy war bonds. Today, it resides in the National Museum of the Pacific War in Fredericksburg, Texas.
On the 50th anniversary of the attack, Sakamaki finally reunited with his ship while he was attending a conference. The sole survivor of his unit, he was moved to tears.