German submarine U-718

German submarine U-718 was a short-lived Type VIIC U-boat built by Nazi Germany's Kriegsmarine for service during World War II. Due to an accident during training exercises five months after completion, U-718 never saw active service in the Kriegsmarine. Built at Hamburg during 1942 and 1943 and taking a year to complete, U-718 was a Type VIIC submarine and was intended for service in the Battle of the Atlantic.

Design
German Type VIIC submarines were preceded by the shorter Type VIIB submarines. U-718 had a displacement of 769 t when at the surface and 871 t while submerged. She had a total length of 67.10 m, a pressure hull length of 50.50 m, a beam of 6.20 m, a height of 9.60 m, and a draught of 4.74 m. The submarine was powered by two Germaniawerft F46 four-stroke, six-cylinder supercharged diesel engines producing a total of 2800 to 3200 PS for use while surfaced, two AEG GU 460/8–27 double-acting electric motors producing a total of 750 PS for use while submerged. She had two shafts and two 1.23 m propellers. The boat was capable of operating at depths of up to 230 m.

The submarine had a maximum surface speed of 17.7 kn and a maximum submerged speed of 7.6 kn. When submerged, the boat could operate for 80 nmi at 4 kn; when surfaced, she could travel 8500 nmi at 10 kn. U-718 was fitted with five 53.3 cm torpedo tubes (four fitted at the bow and one at the stern), fourteen torpedoes, one 8.8 cm SK C/35 naval gun, 220 rounds, and two twin 2 cm C/30 anti-aircraft guns. The boat had a complement of between forty-four and sixty.

Service history
On the 18 November 1943, U-718 was conducting training as part of a "wolfpack" near Bornholm in the Baltic Sea under Oberleutnant zur See Helmut Wieduwilt, when she was accidentally rammed by GS U-476. The submarines had been maneuvering to attack the same target in the dark, and U-476 ran aboard U-718 whilst the submarines were running on the surface. U-718's hatch was closed to prevent water entering the hull, and thus only the seven personnel in the conning tower, including Kapitänleutnant Wieduwilt, survived. The boat's hull was ruptured by the force of the impact, causing the submarine to fill and sink very rapidly, taking 43 sailors to the bottom with her. The survivors were rescued from the water by other German naval units and transferred to other boats.