In February 1945, a Royal Navy submarine destroyed a German Type IX U-boat, U-864, off Norway. It was the first and last time a submarine was able to take out an enemy submarine while submerged.
Near the end of the war, Ralf-Reimar Wolfram and his U-864 took part in a secret mission smuggling jet engine parts, schematics, mercury, engineers, and advisors into Japan. Operation Caesar was tasked with getting the cargo there without the Allied ships seeing them.
The idea was that if Germany failed in their war efforts, the Japanese could use the technology to keep moving forward, buying time for Germany to get back into the game.
The U-864 headed to Norway in December 1944 to get a new snorkel before it left for its mission. However, it did not go as planned, and the mission was pushed back until January 1945.
But, there was another hiccup that the German Navy did not know about. The Allied forces cracked the Enigma code and knew about Operation Caesar. But, in response, they had already bombed a few of the submarine pens.
Tracking The Enemy Sub
U-864 was able to get away without the Allied warships seeing it. However, the Royal Navy did not want the sub to reach its destination. Therefore, the HMS Venturer was tasked with finding and killing the U-864 before it got into open waters.
Lt. Jimmy Launders was the commander of the Venturer. He was a couple of days from the last known position of the U-864 when the sub unknowingly gave away its position.
Wolfram had just ordered the sub to go back to port because its engine was making noise, and he did not want to give away their position. But, Launders already knew where they were.
Using sonar would have given away Launder's edge, so he used a hydrophone to follow them. Launders tracked the U-864 for a while before he launched four torpedos. Wolfram's crew did not know they were under attack until their hydrophone operators picked up the sound of the incoming torpedos.
Wolfram attempted evasive maneuvers and sped up, but it was too late. One out of four torpedoes was a direct hit. The torpedo cracked the pressure hull.
The sub sank to the bottom of the ocean carrying its crew with her. To this day, the Venturer is the only submarine to take out a fellow submarine.