Tuesday, December 08, 2009

Mystery Solved?

The USS Oklahoma, capsized and on fire during the attack on Pearl Harbor. New evidence suggests that a torpedo from a Japanese mini-sub may have delivered the coup de grace that caused the battleship to roll over (Wikipedia photo).

Sixty-eight years after the Japanese attack on Pearl Harbor, one of its biggest mysteries may have been solved.

For years, military historians and naval architects have debated the loss of the USS Oklahoma, one of eight U.S. battleships that were sunk or heavily damaged during the battle. Suffering multiple hits from Japanese torpedoes and bombs, the Oklahoma capsized only eight minutes after the attack began, leaving her starboard side and a part of the keel above water. Only the battleship's masts--mired in the mud of the harbor--keep the Oklahoma from rolling completely upside down.

More than 400 men died in the attack on the World War I-era battle wagon. Many were trapped beneath the decks as the ship began to fill with water and capsize. For days after the attack, survivors pounded on the hull with wrenches and other heavy objects, trying to attract the attention of rescuers. Despite the heroic efforts of shipyard worker Juan DeCastro (who led rescue teams assigned to the Oklahoma), only 32 men were pulled from capsized battleship. The rest perished; the banging from inside the ship's hull began to fade as the men ran out of oxygen.

The sinking of the Oklahoma represented the second-greatest loss of life at Pearl Harbor, ranking only behind the destruction of the USS Arizona. But while historians are relatively sure of what happened to the Arizona--that ship was destroyed by massive explosions that began in her forward magazines--the cause of the Oklahoma's catastrophic roll has been a matter for speculation.

True, the battleship was struck by a number of torpedoes in the opening moments of the attack. But, it was always assumed that all of the torpedoes were dropped by Japanese aircraft. Those weapons weighed 400 pounds and ran relatively shallow (compared to sub-launched torpedoes). Other vessels along Battleship Row on December 7, 1941 sustained similar hits, and settled on an even keel into the harbor bottom, a product of the torpedo's trajectory and valiant efforts at damage control.

So, why did the Oklahoma turn turtle? Researchers believe the answer to that question may lie with a Japanese miniature submarine which has never been accounted for--until now.

It's no secret that the Japanese fleet deployed five mini-subs to penetrate Pearl Harbor and attack U.S. ships within the anchorage. Four of the vessels were scuttled, destroyed or run aground without inflicting any damage. The fifth mini-sub was presumed lost; the boat was never sunk or captured, and there was no evidence it actually entered the harbor.

But that assessment may be changing. As the Los Angeles Times reports, wreckage from that last mini-sub has been located in Pearl Harbor, and there's strong evidence the vessel fired its torpedoes at capital ships anchored along Battleship Row. One of those weapons apparently struck the Oklahoma, causing it to capsize.

The evidence is largely circumstantial, but it is rather compelling. First, the mini-sub's mother ship received a radio transmission on the evening of 8 December--almost 40 hours after the attack. Reporting success of their mission, the last transmission of the mini-sub crew indicated they survived the chaos of the attack and their aftermath.

Parks Stephenson, a maritime historian and former Navy submariner, believes the crew moved their boat to Pearl Harbor's West Loch after the Japanese strike, then scuttled the vessel after radioing their final report.

West Loch was also the site of a 1944 ammunition explosion that destroyed six LSTs (Landing Ship Tank), preparing for the invasion of Saipan. More than 200 sailors died in the accident. Determined to keep the mishap--and the planned operation--a secret, the Navy quickly scooped up the remains of the LSTs and the mini-sub, which was scuttled in the same area. The debris was dumped at sea, three miles south of Pearl Harbor. It was located by divers 50 years later.

Pictures of the undersea wreckage were relayed to Mr. Stephenson, who spotted the distinctive "net cutter" found on Japanese mini-sub. At that point, the historian knew he had located the fifth mini-sub, missing for more than 50 years.

Other evidence also supports the theory. As the Times reports, a photograph taken from a Japanese aircraft above Pearl Harbor appears to show a mini-sub firing a torpedo towards Battleship Row, and a 1942 report to Congress claims the Navy recovered an unexploded, 800-pound torpedo that was apparently aimed at the USS West Virginia. Since no torpedoes were sighted with the mini-sub wreckage, that leaves one of its weapons unaccounted for.

But Mr. Stephenson says that discrepancy can be explained by a post-attack examination of the Oklahoma. After months of painstaking salvage work the battleship was raised and placed in a dry dock, where its guns and other gear were removed. Analysis of the damage revealed that Oklahoma suffered much greater damage than aerial torpedoes could have caused. Based on those findings, it seems quite possible that the "lost" mini-sub may have delivered the final blow that sent the Oklahoma to the bottom, and killed 425 members of her crew.

The mini-sub theory will be presented in greater detail next month, during an episode of the PBS series "Nova."

As for the Oklahoma, the Navy determined that it would be too expensive to repair the battleship, particularly when other surviving dreadnoughts (Maryland, Tennessee, California, Nevada, West Virginia and Pennsylvania) had returned to service, and newer battleships were also available. Stripped of its guns and other important components (and patched up enough to float) the Oklahoma was sold for scrap. En route to a breaking yard in San Francisco, the the hulk and its tow vessels were caught in a storm. Tow lines parted and the Oklahoma was lost again, this time forever.


Neil said...

So what happened to the crew of the mini-sub? The implication is that they went ashore at Pearl Harbor...

Corky Boyd said...

Interesting article.

On the aerial torpedoes, the Japanese devised a very simple fix to prevent the torpedoes from burying themselves in the muck of Pearl Harbor.

Aerial torpedoes launched at 200 mph or so continue their trajectory underwater and often reach 150 feet deep before stabilizing at the preset depth setting. This is no problem in the open ocean, but in a harbor it normally rules out aerial torpedoes.

The Japanese built a simple and flimsy wooden box to fit over the nose of the torpedo. It was strong enough to withstand air loads, but disintigrated when it hit the water. The box slowed the flight of torpedo enough that it wouldn't reach the 40 to 50 foot depths of Pearl Harbor. Very clever!

What happened to the midget sub crew? It is possible, but unlikely they were taken in by sympathetic Japanese on the island. In the fifties I read a book by a P-40 pilot who was shot down during the attack. He bailed out and landed in a sugar cane field near Ewa. He said a laundry truck sped toward him and stopped. When they saw he was American, they sped away.

If the crew did survive, they likely would have told their story by now. More likely they either died or took their own lives to avoid the dishonor of capture.

Unknown said...

Neil--Given Japanese military protocol in such a situation; mission complete, virtually no hope of escape and wishing to avoid the dishonor of capture at any cost, the crew would have (most likely) gone down with the ship.

But that raises another question, namely, why no human remains were discovered with the wreckage of the mini-sub, either in 1944, or during the 1990s.

While the passage of time would explain the lack of remains over the last decade, it's quite possible that human remains might have been found in the West Loch in 1944. The lack of historical evidence in that regard is probably explained by the Navy's desire to cover up the LST debacle, and avoid tipping the Japanese about the pending invasion of Saipan. In the rush to clear debris, Navy salvage crews scooped up everything they could find in the area, including wreckage of the Japanese mini-sub. It's also likely that some of the salvage crews were unaware of what they dumped off Pearl Harbor, or if they were, officers told them to keep quiet.

Bottom line: it's highly unlikely that the Japanese crew survived the scuttling of their sub.

Corky--You are spot-on in your description of the Japanese fix that kept their aerial torpedoes from running too deep. It's also worth remembering that the Imperial Japanese Navy was influenced by the successful British attack on the Italian fleet at Taranto in November, 1940Smaller raid, but it delivered a devastating blow to Mussolini's fleet. And, like Pearl Harbor, the British had to overcome the technical problems associated with an aerial torpedo attack in shallow waters.