Nummer: 18318a
| Area : | Western Area |
| Sea area : | English Channel |
| Date of attack : | 29.07.1944 |
| Nationality of U-boat : | German |
| U-boat : | U 621 |
| Commander : | Stuckmann |
| Grid : | BF 3533 |
| presumed target type : | Steam Freighter |
| presumed tonnage : | 6000 BRT |
| presumed result : | sunk |
| Number of torpedoes/mines : | 1 |
| Used weapon(s) : | Acoustic homing torpedo (gnat) |
| Convoy : | unknown |
| Date of observation : | 29.07.1944 |
| Nationality of target : | British |
| Actual type of target : | Landing Ship Infantry |
| Name of target : | Prince Leopold |
| Year of launch : | 1929 |
| Actual tonnage : | 2938 ts |
| Actual result : | sunk |
| Position of target : | 50.19n 00.53w |
| Footnote : | U-621 hit a ship with a gnat after 1:50 min, which sank. Two hours later another ship was hit with a LUT after a run time of 53 sec. |
| related attacks : | Angriff 1 |
Landing Ship Infantry Prince Leopold ex Belgian Steam Freighter Prince Leopold (bis 1941)
| Convoy : | unknown |