German submarine U-100 was a Type VIIB U-boat of Nazi Germany's Kriegsmarine during World War II.
German Type VIIB submarines were preceded by the shorter Type VIIA submarines. U-100 had a displacement of 753t when at the surface and 857t while submerged. She had a total length of 66.5m (218.2feet), a pressure hull length of 48.8m (160.1feet), a beam of 6.2m (20.3feet), a height of 9.5m (31.2feet), and a draught of 4.74m (15.55feet). The submarine was powered by two Germaniawerft F46 four-stroke, six-cylinder supercharged diesel engines producing a total of NaNPS for use while surfaced, two BBC GG UB 720/8 double-acting electric motors producing a total of 750PS for use while submerged. She had two shafts and two 1.23abbr=onNaNabbr=on propellers. The boat was capable of operating at depths of up to .
The submarine had a maximum surface speed of and a maximum submerged speed of . When submerged, the boat could operate for at ; when surfaced, she could travel at . U-100 was fitted with five 53.30NaN0 torpedo tubes (four fitted at the bow and one at the stern), fourteen torpedoes, one 8.82NaN2 SK C/35 naval gun, 220 rounds, and one 2cm (01inches) anti-aircraft gun. The boat had a complement of between forty-four and sixty.
The boat was launched on 10 April 1940, with a crew of 53, under the command of Kapitänleutnant Joachim Schepke. On her first active patrol, U-100 came into contact with two Allied convoys, OA-198 and OA-204. She shadowed both convoys.
U-100 departed for her second active patrol on 11 September 1940, coming into contact with the Allied convoy HX 72. HX 72 lost 11 ships in total, with U-100 accounting for 7 ships of 50,340 GRT. In the attack on this convoy, while other U-boats stood off to the side and fired their torpedoes to little or no success, U-100 penetrated inside the convoy before attacking, a tactic soon adopted by the C-in-C of U-boats, Admiral Karl Donitz.
After resupplying, U-100 departed for her third active patrol on 12 October 1940. She came into contact with two Allied convoys, HX 79 and SC 7.
U-100 departed on her fourth patrol on 7 November 1940. On 22 November she came into contact with the Allied convoy SC 11 and began to shadow it.
U-100 left for her fifth active patrol on 2 December 1940, sinking two vessels from Convoy OB 256, then a third solo vessel.
U-100 departed on her sixth and what would be her final patrol on 9 March 1941. She approached convoy HX 112 from astern in the pre-dawn hours of 17 March, but was detected at a range of 1,000 meters by the Type 286 radar aboard .[1] U-100 was the first U-boat to be so discovered during World War II; she was rammed and sunk by Vanoc while attempting to submerge.[2] Another destroyer,, was also present.[3] Six of the boat's 53 crew members survived, spending the remainder of the war as POWs. Schepke was not one of them.
| - | Date | Ship | Flag | Tonnage (GRT) | Fate[4] |
|---|---|---|---|---|---|
| 16 August 1940 | Empire Merchant |  | 4,864 | Sunk | |
| 25 August 1940 | Jamaica Pioneer | | 5,471 | Sunk | |
| 29 August 1940 | Dalblair | | 4,608 | Sunk | |
| 29 August 1940 | Hartismere | | 5,498 | Damaged | |
| 29 August 1940 | Astra II | | 2,393 | Sunk | |
| 29 August 1940 | Alida Gorthon |  | 2,373 | Sunk | |
| 29 August 1940 | Empire Moose | | 6,103 | Sunk | |
| 21 September 1940 | Canonesa | | 8,286 | Sunk | |
| 21 September 1940 | Torinia | | 10,364 | Sunk | |
| 21 September 1940 | Dalcairn | | 4,608 | Sunk | |
| 22 September 1940 | Empire Airman | | 6,586 | Sunk | |
| 22 September 1940 | Scholar | | 3,940 | Sunk | |
| 22 September 1940 | Frederick S. Fales | | 10,525 | Sunk | |
| 22 September 1940 | Simla |  | 6,031 | Sunk | |
| 18 October 1940 | Shekatika | | 5,458 | Damaged | |
| 18 October 1940 | Boekelo |  | 2,118 | Damaged | |
| 19 October 1940 | Blairspey | | 4,155 | Damaged | |
| 20 October 1940 | Caprella | | 8,230 | Sunk | |
| 20 October 1940 | Sitala | | 6,218 | Sunk | |
| 20 October 1940 | Loch Lomond | | 5,452 | Sunk | |
| 23 November 1940 | Justitia | | 4,562 | Sunk | |
| 23 November 1940 | Bradfyne | | 4,740 | Sunk | |
| 23 November 1940 | Ootmarsum | | 3,628 | Sunk | |
| 23 November 1940 | Bruse | | 2,205 | Total Loss | |
| 23 November 1940 | Salonica | | 2,694 | Sunk | |
| 23 November 1940 | Leise Maersk | | 3,136 | Sunk | |
| 23 November 1940 | Bussum | | 3,636 | Sunk | |
| 14 December 1940 | Kyleglen | | 3,670 | Sunk | |
| 14 December 1940 | Euphorbia | | 3,380 | Sunk | |
| 18 December 1940 | Napier Star | | 10,116 | Sunk | |
| Sunk: | 135,614 | ||||
| Total loss: | 2,205 | ||||
| Damaged: | 17,229 | ||||
| Total: | 155,048 |