HMS Venturer. Not just another RN World War Two submarine, but a ship with a unique history. Her story reads like an Alistair MacLean novel such as
'Where Eagles Dare' or
'The Guns of Navarone' wherein a small group of people are given a seemingly impossible mission, except this actually happened. She did something that had never been done before, and has never been done since. I'm stunned this hasn't led to a movie.
On 9 February 1945 under the command of Lt Jimmy Launders, HMS/m Venturer was the first, and to date, the only submarine to sink another submarine while both were submerged.
This was quite a feat considering he had to work out a 3-dimensional fire control solution to attack a zig-zagging submerged target, using his passive hydrophones as his prime sensor! After following U-864 for several hours hoping for the German boat to surface, he eventually fired all 4 bow torpedoes at his Target 17.5 seconds apart with different depth settings, the fourth Torpedo hit U-864 midships and she imploded and went to the bottom, sadly taking all hands with her.
The actual target for her mission was to was find and sink U-864 - who was on her way to Japan with Jet engine designs & parts, missile guidance systems (from the V2) and tonnes of Mercury in flasks as part of Germany's Operation Caesar. U-864s approximate position in the North Sea, west of Bergen had been identified by Enigma interceptions of her signals at Bletchley Park. Signalled by Submarine Command, Venturer homed in on the ‘datum’ - Launders then detected her using Hydrophones and latterly confirmed her as the target using his periscope.
Launders tactical genius and the application of his mathematical flair to the huge problems he faced of getting a workable firing solution on a passive target with a variable course, speed and depth that could only be tracked using sound (like a 3-D game of chess with your eyes closed!) all without the aid of a computer. It's hard to believe that Venturer was only his second boat, having left general service (HMS Repulse) in 1941!
Venturer had a successful war, sinking 13 German ships and another U-boat - U771 during her previous 10 patrols - earning him a DSO, he got a bar to that DSO for sinking U-864 and her invaluable cargo.
After the war - Venturer would serve under the Norwegian ensign as HNoMS Utstein until she was scrapped in 1964, Launders served in the RN until he retired as a Captain in 1974, he died in 1988.