German submarine U-591

German submarine U-591 was a Type VIIC U-boat built for Nazi Germany's Kriegsmarine for service during World War II. She was laid down on 30 October 1940 by Blohm & Voss, Hamburg as yard number 567, launched on 20 August 1941 and commissioned on 9 October 1941 under Kapitänleutnant Hans-Jürgen Zetzsche.

Design
German Type VIIC submarines were preceded by the shorter Type VIIB submarines. U-591 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 Brown, Boveri & Cie GG UB 720/8 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-591 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 an anti-aircraft gun. The boat had a complement of between forty-four and sixty.

Service history
The boat's service began on 9 October 1941 with training, followed by active service as part of the 6th U-boat Flotilla. She was transferred to the 11th Flotilla on 1 July 1942 for active service in the North Atlantic operating out of Bergen. The following year, on 1 June 1943, she transferred to 9th Flotilla operating of Brest, France.

In 4 patrols she sank four merchant ships, for a total of, plus one merchant ship damaged.

Wolfpacks
U-591 took part in nine wolfpacks, namely
 * Schlei (21 January – 12 February 1942)
 * Bums (6–10 April 1942)
 * Greif (14–29 May 1942)
 * Nebelkönig (27 July – 13 August 1942)
 * Ungestüm (11–30 December 1942)
 * Sturmbock (21–26 February 1943)
 * Wildfang (26 February – 5 March 1943)
 * Westmark (6–11 March 1943)
 * Seewolf (21–30 March 1943)

Convoy ONS 154
The first victim of Convoy ONS 154 was the 5,701-GRT Norwegian freighter Norse King, the second in column eleven, on 28 December 1942. U-591 torpedo hit her at 20:04. Badly damaged, Norse King attempted to limp to the Azores but was found by GS U-435 and sent to the bottom. U-591’s second success was the badly damaged and abandoned 4,871-GRT United Africa Company freighter Zarian with a single torpedo, although she missed the Baron Cochrane

Convoy SC 121
Having recently returned to sea after a long recovery from gunshot wounds, Hans-Jürgen Zetzsche was on target with Convoy SC 121 when he sighted the Empire Impala, hove-to picking up survivors from the torpedoed Egyptian, on 7 March 1943. Of the combined crew of 80 men, from both Egyptian and Empire Impala, only 3 survived.

Fate
U-591 was sunk on 30 July 1943 in the South Atlantic near Pernambuco in position -8.6°N, -34.56667°W; depth charged by a US Lockheed Ventura aircraft of VB-127. There were 19 dead and 28 survivors.