U-553

U-553. A Type VIIC U-boat of Nazi Germany's Kriegsmarine during World War II. Commissioned in late 1940, it conducted ten war patrols under the command of Kapitänleutnant Karl Thurmann, primarily operating in the North Atlantic and the Gulf of Saint Lawrence. The submarine is best known for sinking the Canadian National steamer SS Caribou in the Cabot Strait in October 1942, an attack that resulted in heavy civilian casualties. U-553 disappeared with all hands in the North Atlantic in January 1943, its exact fate remaining a mystery.

Service history

U-553 was part of the 7th U-boat Flotilla based in Saint-Nazaire for its front-line service. After completing work-up exercises in the Baltic Sea, the submarine was assigned to patrol the vital Allied convoy routes in the North Atlantic. Its operational history was marked by engagements against Convoy SC 42 and Convoy ON 67, contributing to the intense naval conflict of the Battle of the Atlantic. The boat's final patrol commenced from its French base in late December 1942, after which it failed to return, being declared missing by the Kriegsmarine's Befehlshaber der U-Boote.

Construction and design

The submarine was ordered by the Kriegsmarine on 25 September 1939 and its keel was laid down on 21 November 1939 at the Blohm & Voss shipyard in Hamburg. Designated as yard number 529, it was launched on 7 November 1940. As a Type VIIC boat, U-553 was a workhorse of the U-boat fleet, displacing 769 tonnes surfaced and 871 tonnes submerged. Its design featured a pressure hull strengthened for deep diving, five torpedo tubes, and a deck-mounted 8.8 cm SK C/35 naval gun. It was powered by twin MAN diesel engines for surface running and Siemens-Schuckert electric motors for submerged operations.

Patrols and engagements

U-553 undertook ten war patrols, sinking a total of twelve ships and damaging two others. Its first patrol began in August 1941, resulting in the sinking of the British freighter SS Stork southwest of Iceland. During its second patrol, the boat attacked Convoy SC 42, sinking the Greek freighter *Anna Bulgaris*. A significant engagement occurred in October 1942 during its ninth patrol, when U-553 torpedoed and sank the passenger ferry SS Caribou in the Cabot Strait, a vessel traveling from North Sydney to Port aux Basques, causing the loss of 136 lives. Other notable victims included the Panamanian tanker MT British Prudence and the American freighter SS West Irmo.

Fate

U-553 departed Saint-Nazaire for its tenth and final patrol on 23 December 1942. The last communication received from the boat was a weather report transmitted on 20 January 1943 from grid square BE 29 in the North Atlantic, east of Newfoundland. No further signals were received, and the boat was posted missing on 8 February 1943. Post-war assessments by the Admiralty's Naval Intelligence Division and historians have suggested several possible causes for its loss, including an attack by Royal Canadian Air Force aircraft, an accidental diving disaster, or striking a naval mine from an Allied field. No wreck has been conclusively identified, leaving its fate unresolved.

Commanding officers

* 23 December 1940 – 20 January 1943: Kapitänleutnant Karl Thurmann Thurmann, a recipient of the Knight's Cross of the Iron Cross, commanded U-553 for its entire operational life, from commissioning through all ten patrols until its disappearance. He was credited with sinking over 50,000 GRT of Allied shipping. Prior to his command, Thurmann served as a watch officer on the U-23 under the famed Kapitänleutnant Otto Kretschmer.

Category:World War II submarines of Germany Category:Type VIIC submarines Category:Missing submarines