German submarine U-864

Ship caption= }} German submarine U-864 was a Type IXD2 U-boat of Nazi Germany's Kriegsmarine in World War II. On 9 February 1945, it became the only submarine in history to be sunk by an enemy submarine while both were submerged. ''U-864'' was sunk by the British submarine , and all 73 men on board died. Design German Type IXD2 submarines were considerably larger than the original Type IXs. U-864 had a displacement of when at the surface and while submerged. The U-boat had a total length of ,…