World War 2 History: The Only Time in History a Submerged Submarine Sank Another Submerged Submarine
Sub To Sub
In movies and books about the Cold War and whatever era we are in now and wherever we're going, it is not uncommon for two submarines to fight each other deep below the ocean's surface. Usually, one emerges victorious, while the other, holed or blown to pieces, disappears into the freezing, inky depths below. In actuality, there is only one documented instance in history of a submerged sub attacking and destroying another submerged sub.
The German U-Boat U-864 was assigned to carry out Operation Caesar, a plan to take critical advanced war supplies and design documents to Japan, in December 1944. U-864 was a large Type IX U-Boat, displacing 1,800 tons and designed for long ocean-going missions with a range of over 18,000 miles. A series of mishaps and Allied bombings delayed her sailing until February 1945, when she left Bergen, Norway for the Far East. She was carrying parts and drawings for jet fighter aircraft and V-2 missile guidance systems as well as 67 tons of mercury stowed in more than 1,800 steel bottles. The mercury was critical for the manufacture of explosives, especially detonators. On board were 73 men, including two Japanese engineers and her captain, Ralf-Reimar Wolfram.
During the months before her departure, the British had intercepted and deciphered Enigma-encoded messages and knew all about U-864's mission. The Admiralty diverted the British submarine HMS Venturer to search for U-864 along Norway's west coast. It was a small V-Class submarine, displacing 740 tons, with a crew of 37, including its captain, 25-year-old Jimmy Launders, who was something of a boy wonder with a genius for mathematics.
On February 9, U-864's bad luck continued when one of her engines started misfiring. Captain Wolfram informed headquarters at Bergen he was returning for repairs and was told that an escort would meet them the next day. Unfortunately, the misfiring greatly increased the submarine's noise signature and Venturer picked it up and decided to investigate.
U-864 Stays Submerged
While at periscope depth, Venturer spotted U-864's periscope or snorkel and began tracking the German sub, waiting for it to surface in order to get a good shot at it. U-864 soon detected it was being followed and remained under the surface, where it knew it would be safe from the enemy submarine, and Wolfram commenced zig-zag procedures. For several hours Venturer followed U-864, but it was apparent that the German was not going to surface, so Launders began to calculate a three-dimensional firing solution. A ship on the surface moves in only two dimensions, forward/backward and left/right, and is difficult enough to hit. U-864 had an extra dimension to play with-- up/down-- and such a complex solution had never been tried before, since the mathematics were so difficult. Adding to the problem was the fact that surface targets were visually acquired, while the three-dimensional location of U-864 was based on sound alone.
Launders and his crew bent to the task of calculating where U-864 would be four minutes in the future, applying all they had observed in the hours tracking her as she zigged and zagged and dove and rose. Finally, they had the best solution they could come up with and readied their four forward torpedoes (they only had eight torpedoes total). One by one the torpedoes were fired, each at a different angle and target depth, 17 seconds apart. After the last torpedo launched, Launders immediately dove to evade any retaliation. Upon hearing the torpedoes in the water, Wolfram also ordered a dive. For four minutes the torpedoes ran. The first one missed. The second one missed. The third one missed. But the U-864 had dived right into the path of the last torpedo, which struck her. She imploded and split in two, taking all hands with her to the bottom 500 feet below the surface.
Several awards were given to Venturer's crew and Launders himself received the Distinguished Service Order, considered second only to the Victoria Cross. The techniques he used became the basis of modern torpedo computer targeting systems. Launders stayed in the Navy until he retired in 1962 with the rank of Commander and died in 1988 at the age of 69.
The wreckage of U-864 was discovered in 2003 about three miles west of the island of Fedje, Norway. It is classified as a War Grave, however the bottles containing the mercury are deteriorating and an estimated 9 lbs of the toxic substance leaks into the waters every year, contaminating all the sea life in the area. Norway has suggested entombing it in 40 feet of sand and encasing that with concrete or gravel, but critics are concerned about future leakage. A plan to raise it has been put forth but, at a cost of $150 million, the plan has been postponed.