Siegfried von Forstner Ships attacked Ships attacked

| Date_ | Ship | Nationality | Tonnage | Fate |
|---|---|---|---|---|
| 16 May 1941 | Llangibby Castle | Great Britain | 11951 | Damaged |
| 13 April 1942 | Empire Progress | Great Britain | 5249 | Sunk |
| 30 April 1942 | Ashkhabad | Soviet Union | 5284 | Sunk |
| 2 May 1942 | USS Cythera | USA | 602 | Sunk |
| 2 November 1942 | Dalcroy | Great Britain | 4558 | Sunk |
| 2 November 1942 | Empire Antelope | Great Britain | 4945 | Sunk |
| 2 November 1942 | Empire Leopard | Great Britain | 5676 | Sunk |
| 2 November 1942 | Empire Sunrise | Great Britain | 7459 | Damaged |
| 2 November 1942 | Rinos | Greece | 4649 | Sunk |
| 7 February 1942 | Afrika | Great Britain | 8597 | Sunk |
| 7 February 1942 | Daghild | Norway | 9272 | Damaged |
| 7 February 1942 | Henry R. Mallory | USA | 6063 | Sunk |