German submarine U-870

German submarine U-870 was a Type IXC/40 U-boat of Nazi Germany's Kriegsmarine built for service during the Second World War. She was ordered on 25 August 1941, and laid down on 29 April 1943 at Bremen, Germany. She was launched on 29 October 1943 and commissioned on 3 February 1944.

Design
German Type IXC/40 submarines were slightly larger than the original Type IXCs. U-870 had a displacement of 1144 t when at the surface and 1257 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 6.86 m, a height of 9.60 m, and a draught of 4.67 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 13850 nmi at 10 kn. U-870 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 Flak M42 as well as two twin 2 cm C/30 anti-aircraft guns. The boat had a complement of forty-eight.

Service history
For her one patrol, she had one commander, Korvettenkapitän Ernst Hechler, who was awarded the Knight's Cross of the Iron Cross. Over her career she claimed two warships sunk, total of 1,960 tons, one warship damaged for a total of 1,400 tons, and two ships a total loss, total of. On 20 December 1944, U-870 attacked a small group of landing ships, damaging USS Fogg (DE-57) and sinking the 1,625-tons vessel USS LST-359. The U-boat was then attacked by a British aircraft from No. 220 Squadron RAF but got away, also evading two hunter-killer groups of vessels.

Fate
She was sunk on 30 March 1945 at Bremen by US bombs.