Events
On This Day - April 28
| 1906 | B 9 (I 29) | Completed |
| 1941 | P 36 | Launched |
| 1943 | Unshaken (P 54) | HMS Unshaken sinks the Italian torpedo boat Climene |
| 1943 | Usurper (P 56) | HMS Usurper makes a torpedo attack on the German submarine U-467 in the Norwegian Sea. The target was not hit. |
| 1944 | Sportsman (P 229) | HMS Sportsman torpedoes and sinks the German merchant Leneburg north of Iraklion, Crete, Greece. |
| 1944 | Spark (P 236) | Completed |
| 1947 | P 555 | Sunk as target |
| 1984 | Turbulent (S 87) | Completed |
