In the midst of World War II, the Battle of the Atlantic saw intense naval engagements between Allied and Axis powers. One of the most unusual encounters occurred when the British submarine HMS Venturer engaged and ultimately sank the German submarine U-864. This clash took place off the coast of Fedje, Norway, on February 9, 1945. Venturer, commanded by Lieutenant Commander James O. Lancaster, tracked U-864, which had been tasked with delivering essential materials, including advanced technology for German long-range missiles, to Japan.

The encounter began when Venturer, after extensive monitoring and calculation, fired torpedoes at U-864 using a method called 'fire control' that allowed for an accurate shot despite the dynamic underwater environment. The innovative approach proved successful, as one of the torpedoes struck U-864, sinking it and marking a significant moment in the war. This incident is particularly noteworthy as the only recorded case of a submarine sinking another submarine engaged in combat, showcasing both the tactical evolution of warfare and the desperation of the German navy at that stage of the war.

The sinking of U-864 not only shifted the tide of maritime engagements but also disrupted German supply lines. The effectiveness of HMS Venturer's attack contributed to the growing inferiority experienced by Germany’s U-boat fleet as the Allies continued to strengthen their position in the Atlantic. The incident exemplified the critical role of submarines in naval warfare during World War II and highlighted the advancements in torpedo technology and submarine tactics that defined the period.