Action of 9 February 1945

 

u-864_mapThe Action of 9 February 1945 refers to the sinking of the U-boat U-864 in the North Sea off the Norwegian coast during the Second World War by the Royal Navy submarine HMS Venturer.

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This action is the first and so far only incident of its kind in history where one submarine has intentionally sunk another submarine in combat while both were fully submerged.

U-864 was a Type IX U-boat, designed for ocean-going voyages far from home ports with limited re-supply. She was on a long-range, covert mission codenamed Operation Caesar to deliver highly sensitive technology to Germany’s wartime ally, the Empire of Japan.

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Commanded throughout her entire career by Korvettenkapitän Ralf-Reimar Wolfram,she served with the 4th U-boat Flotilla undergoing crew training from her commissioning until 31 October 1944. She was then reassigned to the 33rd U-boat Flotilla.

U-Boot-Kommandant Ralf-Reimar Wolfram

On 6 February 1945, U-864 passed through the Fedje area without being detected, but on 9 February  the HMS Venturer ,under the command of 25-year-old Jimmy Launders, heard U-864s engine noise. Launders had decided not to use ASDIC since it would betray his position and spotted the U-boat’s periscope as her captain looked for his escort.

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In an unusually long engagement for a submarine, and in a situation for which neither crew had been trained, Launders waited 45 minutes after first contact before going to action stations. Launders was waiting for U-864 to surface and thus present an easier target. Upon realising they were being followed by the British submarine and that their escort had still not arrived, U-864 zig-zagged underwater in attempted evasive manoeuvres, with each submarine occasionally risking raising her periscope.

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Venturer had only eight torpedoes as opposed to the 22 carried by U-864. After three hours Launders decided to make a prediction of U-864s zig-zag, and released a spread of his torpedoes into its predicted course. This manual computation of a firing solution against a three-dimensionally manoeuvring target was the first occasion on which techniques were used and became the basis of modern computer-based torpedo targeting systems. Prior to this attack, no target had been sunk by torpedo where the firing ship had to consider the target’s position in three-dimensional terms, where the depth of the target was variable and not a fixed value. The computation thus differs fundamentally from those performed by analogue torpedo fire-control computers which regarded the target in strictly 2D terms with a constant depth determined by the target’s draught.

The torpedoes were released in 17 second intervals beginning at 12:12, and all taking four minutes to reach their target.(picture below are not the actual torpedoes)

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Launders then dived Venturer suddenly to evade any retaliation. U-864 heard the torpedoes coming, dived deeper, and turned away to avoid them. The first three torpedoes were avoided, but U-864 unknowingly steering into the path of the fourth. Exploding, U-864 split in two, and sank with all hands coming to rest more than 150 metres (490 ft) below the surface. Launders was awarded a bar to his DSO for this action.

During her career she also sank five merchant ships

31Dec-DayHistory

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