Events
On This Day - December 20
| 1938 | Ursula (N59) | Completed |
| 1942 | Safari (P211) | HMS Safari torpedoes and heavily damages the Italian auxiliary patrol vessel F 139/Constantina in thbe Gulf of Hammamet, Tunisia. The damaged Italian ship was declared a total loss. |
| 1942 | Unshaken (P54) | HMS Unshaken attacks the French merchant Oasis with gunfire off Genova, Italy. No damage is inflicted. |
| 1943 | Vox (P67) | Completed |
| 1944 | P511 | Returned to the USN but remained laid up in Britain. |
| 1944 | P555 | Returned to USN |
| 1968 | Churchill (S46) | Launched |
