September | ||||||
| U-boat | Crew | Dead | Surv. | Notes | ||
| 14 Sep 1939 | U-39 | 44 | 0 | 44 | Warship | |
| 20 Sep 1939 | U-27 | 38 | 0 | 38 | Warship | |
October | ||||||
| U-boat | Crew | Dead | Surv. | Notes | ||
| 8 Oct 1939 | U-12 | + | 27 | 27 | 0 | Lost to mines |
| 13 Oct 1939 | U-40 | 48 | 45 | 3 | Lost to mines | |
| 13 Oct 1939 | U-42 | 46 | 26 | 20 | Warship | |
| 14 Oct 1939 | U-45 | + | 38 | 38 | 0 | Warship |
| 25 Oct 1939 | U-16 | + | 28 | 28 | 0 | Warship |
November | ||||||
| U-boat | Crew | Dead | Surv. | Notes | ||
| 29 Nov 1939 | U-35 | 43 | 0 | 43 | Warship | |
December | ||||||
| U-boat | Crew | Dead | Surv. | Notes | ||
| 4 Dec 1939 | U-36 | + | 40 | 40 | 0 | Warship |
9 U-boats lost in 1939 (204 men died and 148 men survived those losses).
+ means that the boat was lost with all hands.
U-boats scuttled at sea after battle damage are considered war losses and are shown above.