German Type VIIC submarines were preceded by the shorter Type VIIB submarines. U-628 had a displacement of 769t when at the surface and 871t while submerged. She had a total length of 67.1m (220.1feet), a pressure hull length of 50.5m (165.7feet), a beam of 6.2m (20.3feet), a height of 9.6m (31.5feet), 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 Brown, Boveri & Cie 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-628 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 a 2sp=usNaNsp=us C/30 anti-aircraft gun. The boat had a complement of between forty-four and sixty.
The boat's service began on 25 June 1942 with training as part of the 5th U-boat Flotilla. She was transferred to the 1st Flotilla on 1 December 1942 for active service in the North Atlantic.
In four patrols she sank four merchant ships, for a total of, plus three merchant ships damaged.
U-628 took part in six wolfpacks, namely:
U-628 was sunk on 3 July 1943 in the North Atlantic NW of Cape Ortegal in position 44.1833°N -53°W; bombed and depth charged by RAF Liberator aircraft (FL963) of 224/J Squadron out of RAF St Eval in Cornwall. All 49 hands were lost.
| Date | Ship Name | Nationality | Tonnage (GRT) | Fate[1] | |
|---|---|---|---|---|---|
| 29 December 1942 | Lynton Grange |  United Kingdom | 5,029 | Sunk | |
| 23 February 1943 | Glittre |  Norway | 6,409 | Damaged | |
| 23 February 1943 | Winkler |  Panama | 6,907 | Damaged | |
| 24 February 1943 | Ingria | Norway | 4,391 | Sunk | |
| 25 February 1943 | Manchester Merchant | United Kingdom | 7,264 | Sunk | |
| 17 April 1943 | Fort Rampart | United Kingdom | 7,134 | Damaged | |
| 5 May 1943 | Harbury | United Kingdom | 5,081 | Sunk |