German submarine U-570 was a Type VIIC submarine of the Kriegsmarine that was captured and commissioned into the Royal Navy as HMS Graph (P715). She was the only German U-boat to be taken into Allied service and to fight for both sides in World War II.
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History
Kriegsmarine
She was laid down by Blohm & Voss at Hamburg on 21 May 1940 and commissioned on 15 May 1941. She completed one training voyage between 15 May 1941 and 1 August 1941. On 23 August 1941 she departed from Trondheim, Norway under the command of Kapitänleutnant Hans-Joachim Rahmlow. On 27 August 1941 in the North Atlantic south of Iceland, in position 62°15′N 18°35′W / 62.25°N 18.583°W, she was attacked and damaged by a depth charge from an RAF Lockheed Hudson bomber of 269 Squadron
Unable to submerge, the crew of U-570 displayed a white sheet on the deck of the boat. The Hudson circled the crippled U-boat until assistance arrived, first in the form of a PBY Catalina flying boat followed by the Anti-Submarine Trawler Northern Chief, later assisted by the destroyers HMS Burwell and HMCS Niagara. By this time, it had become dark. The German crew abandoned plans to scuttle the boat as the Northern Chief signaled she would open fire and not rescue survivors from the water if they did this. Instead, they spent the night destroying every piece of equipment on the boat they could. They were removed from the submarine the next day.
The submarine was towed to Þorlákshöfn, Iceland, and beached there for essential repairs, then towed to Barrow-in-Furness where she was fully repaired. By the time the Royal Navy had taken possession of U-570 the German submariners had destroyed all their code books and coding equipment. As a consequence of this, there was no need to keep her capture secret, she would later be displayed to journalists and her capture reported in the British press[1]. The capture of several other submarines, such as the U-110 (which had sunk whilst under tow) was kept secret because their codebooks and Enigma machine had been seized.
On the 3rd of October, she reached the UK, manned by a Royal Navy prize crew, under the command of Lieutenant George Colvin, previously the commander of HMS Sunfish, with Lieutenant Peter Marriott as his second in command [1]. Marriott would later command HMS Graph.[2].
Her repair at the Vickers shipyard in Barrow was complicated by bomb damage to her bow, her plating had been buckled, trapping four, electrically powered, G7e torpedoes. The Royal Navy's Department of Torpedoes and Mines Investigations was extremely anxious to examine them and dispatched Captain Ashe Lincoln and Lieutenant Martin Johnson to retrieve them. The dock was evacuated while a volunteer shipyard worker cut the armed torpedoes free with an oxyacetylene cutter, under Lincoln's and Johnson's supervision. They then disarmed the torpedoes - an exceptionally dangerous task. For this, Johnson was awarded the George Medal. [3]
Royal Navy
U-570 was commissioned into the Royal Navy as HMS Graph on 19 September 1941, and assigned the Royal Navy pennant number N46. She was given a name beginning with a 'G' to signify German, i.e., denoting that Graph was a captured vessel. The name Graph was also chosen owing to the extensive testing (and therefore "Graphs" drawn up) the Royal Navy carried out on U-570 to determine the exact capabilities of that class of U-Boat. She saw active service in 1942 and 1943.
On 21 October 1942, in the Bay Of Biscay, about 50 nautical miles (90 km) north-north-east of Cape Ortegal (44°31′N 7°25′W / 44.517°N 7.417°W,), she encountered the U-333. Four torpedoes were fired but all missed. In December 1942, HMS Graph sighted the German cruiser Admiral Hipper on her return to Altenfjord following the Battle of the Barents Sea, but Hipper was traveling too fast to be attacked. Three hours later Graph sighted one German destroyer towing a second, and attacked. However, her torpedoes missed.
Defects, exacerbated by a shortage of spare parts, led to her being placed in reserve, and she was decommissioned from active service in February 1944. She was being towed by HMS Allegiance to the Clyde for scrapping when she ran aground on the west coast of Islay, Scotland, on 20 March 1944. She was partially salvaged and scrapped in 1947. Some remains of HMS Graph remained visible at low tide on the rocks near Saligo beach on the West coast of Islay at least into the 1970s, with the pressure casing of the conning tower and periscope tube clearly visible (the cladding and railings etc all washed off in the Atlantic storms many years before.)
Although her service was of little benefit to the Royal Navy, the intelligence gained from her examination was of great value. It was discovered that her auxiliary machinery was on rubber mountings, to quieten the boat by reducing sound transmission into the hull.[4]. Also, during the early part of the war, Royal Navy depth charges could not be set to detonate deeper than 170 metres (560 ft) - U-boats were thought to have a maximum depth of 115 metres (380 ft). In fact, Type VII U-boats had a test depth of 230 metres (750 ft) and could thus dive beyond the reach of British depth charges, a fact only revealed by the capture of Graph. Depth charges were soon modified to take account of this[5].
One of the Kriegsmarine flags of the U-570 was presented to the Hudson bomber pilot, Sqn Ldr Thompson, and is now part of the collection of the RAF Museum.
See also
- HM Submarine X2 - Italian Submarine captured and taken into service by the Royal Navy.
- HMS Seal (N37) - Royal Navy submarine, captured and taken into service by the Germans.
References
- ^ a b "Captured U-Boat in Port". The Times: p. 4. 1941-10-04.
- ^ "HMS Graph (P 715)". HMS Graph (P 715). uboat.net. http://www.uboat.net/allies/warships/ship/7751.html. Retrieved on 2009-03-15.
- ^ "Lt-Cdr Martin Johnson". The Daily Telegraph. 2004-07-14. http://www.telegraph.co.uk/news/obituaries/1466843/Lt-Cdr-Martin-Johnson.html.
- ^ Bud, Robert; Gummett, Philip (2002). Cold War, Hot Science: Applied Research in Britain's Defence Laboratories, 1945-1990. NMSI Trading Ltd. p. 166. ISBN 1900747472.
- ^ Macintrie, Donnald (2004). U-Boat Killer: Fighting the U-Boats in the Battle of the Atlantic. Rigel Publications. ISBN 1898799784.
External links
- U-570 and HMS Graph from uboat.net
- U-570 at Bases Sous-Marines
- The White Flag on U 570? 269 Squadron website.
Categories: Type VII U-boats | Captured U-boats | Royal Navy submarines | U-boats of World War II | U-boats commissioned in 1941
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