Japanese Midget Subs Used in Pearl Harbor Attack

New facts have surfaced about the role of small submarines the Japanese used in the surprise bombing on Pearl Harbor. That unprovoked attack pushed the United States into WWII 75 years ago.

Military officials always acknowledged that five midget submarines were part of the surprise attack. Until recent years, however, those historians believed that the small underwater boats failed to inflict any damage to the U.S. fleet stationed on the Hawaiian island of Oahu.

Research discoveries from underwater explorations conducted by two respected broadcasting companies—The History Channel and the Public Broadcasting Service (PBS)—recently uncovered new evidence that led to speculation about the damage inflicted to at least one U.S. battleship.

Japanese Zeros launched from aircraft carriers

This evidence includes newly obtained aerial pictures taken by the pilots of Japanese fighter airplanes, called Zeros, during the attack. The pictures show that two of the small submarines sailed into the harbor and one of the midget subs succeeded in helping to sink the USS Oklahoma. The USS Arizona was sunk inside Pearl Harbor by torpedoes launched from Zeros.

Six other battleships sitting helplessly on battleship row were badly damaged. The damaged ships were repaired and later participated in America’s naval war against Japan.  

Hundreds of pictures were taken by the attacking aircraft and by Americans on the ground during the Sunday morning attack on December 7, 1941. Photographs show the battleship USS Oklahoma exploding upwards before it capsized and sank into the harbor. That evidence plus grainy, out-of-focus pictures from attacking Zeros, indicate at least one torpedo launched underwater by a small submarine hit the battleship.

Because the midget subs used torpedoes with almost twice the destructive power of the ones carried by attacking airplanes, the evidence of the battleship exploding into the air has convinced some historians and photo experts that the USS Oklahoma received major damage from one of the midget submarines.

USS Oklahoma explosion from torpedo hit

Underwater wreckage of the fifth midget sub was uncovered near the entrance to the harbor in August, 2009. The ship’s torpedo tubes were empty, indicating they were fired and may have hit the USS Oklahoma. Bodies of the two-man crew remain inside the wreck that was too badly damaged to raise. A PBS Nova broadcast named “Killer Subs in Pearl Harbor” explores the new evidence of the effectiveness of the surprise Japanese weapon.   

USS Arizona Memorial

Photo evidence of a second midget submarine getting into the harbor shows that ship firing two torpedoes that missed any ships. The two stray torpedoes exploded into a wooden dock far behind the eight battleships sitting on battleship row.

A Japanese Armada of more than 30 ships launched a two-wave attack of fighter/bombers from six aircraft carriers positioned several miles off the coast of Hawaii. More than 400 airplanes rested on the top of the carriers.

The Imperial Naval Fleet stayed so far off shore that the airplanes had to fly almost 90 minutes to reach the U.S. target. It was an amazing feat of using stealth tactics and the element of surprise in an attack that decimated most of America’s naval fleet. More than 2,400 Americans, both military and civilian, died during the attack that began slightly before 8 a.m. Sunday.

The midget U-boats rode on top of submarines that traveled underwater and released the small subs close to the opening of Pearl Harbor. A two-man crew inside the midget submarines had to endure extreme heat that was generated by battery-powered motors that drove twin propellers.

The crew had just enough room to steer the small U-boats and operate a periscope. Most of the cabin was filled with batteries that filled the hot cabin with acrid smells and made the air inside the subs hard to breathe. The crew had very little time to get into the harbor, fire their torpedoes, and retreat to try to be rescued by the mother submarines. They could operate the subs at full power, about 22 mph underwater, for less than one hour.  

The name “midget submarines” is misleading in describing the size of the small attack subs. Measuring about 80 feet long and six feet wide, the small boats were about 1/3rd the length of a full-sized submarine. Deep water exploration submarines today are a fraction of that size. 

Midget Submarines

Each of the small submarines carried two powerful torpedoes attached on top of the ships’ hulls. The torpedoes, each measuring 18 feet long, had twice the destructive power of the ones dropped by the Zeros. Massive recoil from a fired torpedo rocked the midget subs out of the shallow harbor and left a distinctive plum of water from the twin propellers as they broke the surface.

It’s the water spray, called a rooster tail, photo interpreters saw on the captured wartime photography. That’s how they concluded that two of the small subs made the almost impossible trip into the shallow harbor, shot their four torpedoes, and then skillfully sailed out as they tried to get into deep water.

One of the subs sank near the mouth of Pearl Harbor after being hit with depth charges from American ships. Another small sub ran onto a beach on the east side of Oahu. The pilot was captured and became America’s first prisoner of war.  The submarine was put on a tour of the United States to promote the sale of War Bonds.

The Japanese planes disabled America’s entire battleship fleet but fell short of completing the job. Before sending a third air attack that would have completed the destruction to the critical equipment and thousands of gallons of fuel stored on Pearl Harbor, the Imperial Armada retreated back to Japan.

The attackers planned to destroy the three Pacific Fleet aircraft carriers that were assigned to Pearl Harbor. Fortunately, the Lexington, Enterprise and Saratoga were conducting training maneuvers thousands of miles away from Pearl Harbor.

Not knowing when the U.S. carriers were due to return, the admirals in charge of the Japanese fleet feared that their ships could be destroyed by U.S. fighter planes. Retreating before finishing the job was a terrible mistake by the Japanese attackers and an opportunity for the American forces to use their aircraft carriers in the offensive that became World War II.

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