German submarine U-509

German submarine U-509 was a Type IXC U-boat of Nazi Germany's Kriegsmarine during World War II. The submarine was laid down on 1 November 1940 at the Deutsche Werft yard in Hamburg as yard number 305. She was launched on 19 August 1941, and commissioned on 4 November 1941 under the command of Korvettenkapitän Karl-Heinz Wolff.

The U-boat served with the 4th U-boat Flotilla for training, before being assigned to the 10th U-boat Flotilla from 1 July 1942, for front-line service.

Design
German Type IXC submarines were slightly larger than the original Type IXBs. U-509 had a displacement of 1120 t when at the surface and 1232 t while submerged. The U-boat had a total length of 76.76 m, a pressure hull length of 58.75 m, a beam of 6.76 m, a height of 9.60 m, and a draught of 4.70 m. The submarine was powered by two MAN M 9 V 40/46 supercharged four-stroke, nine-cylinder diesel engines producing a total of 4400 PS for use while surfaced, two Siemens-Schuckert 2 GU 345/34 double-acting electric motors producing a total of 1000 shp for use while submerged. She had two shafts and two 1.92 m propellers. The boat was capable of operating at depths of up to 230 m.

The submarine had a maximum surface speed of 18.3 kn and a maximum submerged speed of 7.3 kn. When submerged, the boat could operate for 63 nmi at 4 kn; when surfaced, she could travel 13450 nmi at 10 kn. U-509 was fitted with six 53.3 cm torpedo tubes (four fitted at the bow and two at the stern), 22 torpedoes, one 10.5 cm SK C/32 naval gun, 180 rounds, and a 3.7 cm SK C/30 as well as a 2 cm C/30 anti-aircraft gun. The boat had a complement of forty-eight.

First patrol
U-509 sailed from Kiel on 25 June 1942, across the Atlantic, into the Caribbean Sea and along the coast of South America, without any successes. She arrived at her new home port of Lorient in occupied France on 12 September after 80 days at sea.

Second patrol
U-509 departed from Lorient on 15 October 1942, now under the command of Oberleutnant zur See Werner Witte. Operating in the waters west of the Canary Islands as part of wolfpack Streitaxt (English : "Battle axe") she attacked Convoy SL 125, sinking four ships and damaging three more.

Convoy SL 125
At 17:40 on 26 October the U-boat attacked the 7,705 GRT British tanker Anglo Mærsk, a straggler, with a single torpedo with no apparent effect. However the damaged ship was sunk at 21:06 the next day by GS U-604. The entire crew: master, 32 crewmen, and two gunners, landed at Hierro Island, Canary Islands, on 27 October.

At 22.33 and 22.38 hours on 27 October, U-509 fired torpedoes at the convoy and sank two British merchant ships. The 7,951 GRT Pacific Star did not sink immediately, but the crew abandoned ship, and she was last seen on 30 October, very low in the water, and probably sank shortly afterwards. The 6,148 GRT Stentor was the ship of the vice-commodore of the convoy Captain Richard Hart Garstin, CBE, RNR, and was carrying 125 passengers, including 26 army personnel, 11 nursing sisters and six naval staff members. The master, Vice-Commodore, 20 crewmen, three army personnel, four nurses and 15 passengers were lost. 93 crew members, seven gunners and 107 passengers were picked up by HMS Woodruff (K53).

On 28 October, U-509 fired five torpedoes at the convoy and hit two more British merchant ships, while on 10 November, the fourth engineer and 18 men landed at La Orotava, Tenerife, Canary Islands, after being adrift for 14 days. The 5,178 GRT Hopecastle was badly damaged. Three crewmen and two gunners were lost, and her crew abandoned ship. The master and 20 survivors were picked up by the British merchant ship Mano, and another 19 survivors later landed at Funchal, Madeira. Around 05:00 on 29 October, the abandoned Hopecastle was hit by torpedoes from GS U-203, but the ship stayed afloat and was finally sunk at 10:10 by gunfire.

At 22:16 on 29 October 1942, the U-boat hit the 7,131 GRT British merchant ship Corinaldo with a single torpedo. The ship, loaded with 5,141 tons of frozen meat from Buenos Aires, dropped out of the convoy and was abandoned. Seven crew members and one gunner were lost. The master, 41 crewmen and eight gunners were picked up by HMS Cowslip (K196). At 02:07 the next day, GS U-659 struck the ship with two torpedoes, but she remained afloat. At 04:16 on the 30th the wreck was finally sunk by a torpedo and gunfire from GS U-203.

Finally, at midnight on 30 October the U-boat torpedoed and sank the 4,772 GRT British merchant ship Brittany near Madeira. Twelve crewmen, one gunner, and one passenger were lost. The master, 32 crewmen, seven gunners, and three passengers were picked up by the British auxiliary patrol vessel HMS Kelantan (F166).

U-509 then sailed for the waters off Morocco to operate against the Allied ships taking part in the Operation Torch landings. The U-boat operated for three days in waters less than 200 ft deep and was constantly bombed and depth charged by Allied surface vessels and aircraft. U-509 received some damage, forcing her to abort the patrol and return to Lorient on 26 November after 43 days at sea.

Third patrol
U-509's next patrol took her far south, to the waters off South Africa. Leaving Lorient on 23 December 1942, she made her first kill at 02:19 on 10 February, sinking the 4,937 GRT British merchant ship Queen Anne eight miles south-south-west of Cape Agulhas. The U-boat was attacked by the ASW trawler HMS St. Zeno (FY280) with gunfire and seven depth charges, but was not damaged and made her escape. The master, two crewmen and two gunners from Queen Anne were lost. Eighteen survivors were picked up by St. Zeno, while 22 survivors later made landfall at Bredasdorp.

The U-boat struck again at 22:00 on 2 April, torpedoing the 7,129 GRT British passenger ship City of Baroda of Convoy NC-9 north-west of Cape Town. The badly damaged vessel was towed to Lüderitz Bay, South West Africa and beached. Later she broke in two, and was declared a total loss. One crewman and seven passengers were lost. The master, 124 crewmen, four gunners, and 196 passengers were picked up by HMS Cape Warwick (FY167).

U-509 returned to Lorient on 11 May after a voyage lasting 140 days.

Fourth patrol
The U-boat's final patrol began on 3 July 1943, under the command of the newly promoted Korvettenkapitän Werner Witte, and sailing south-west to the waters south of the Azores. There on 15 July, north-west of Madeira, in position 34.03333°N, -26.01667°W, she was sunk with all hands by aerial FIDO torpedoes from a Grumman TBF Avenger bombers of Navy squadron VC-29 flying from the escort carrier USS Santee (CVE-29).

Wolfpacks
U-509 took part in two wolfpacks, namely:
 * Streitaxt (20 October – 2 November 1942)
 * Schlagetot (9 – 15 November 1942)