| 01.07.1940-28.07.1940 | zur Verfügung U-Boot-Waffe / Befehlshaber der U-Boote Org., U.W.O-Artillerielehrgang Schiffsartillerieschule, Kiel-Wik. (was attached to the U-Boat service. Artillery Training in Naval Artillery School.) |
| 29.07.1940-30.09.1940 | U-Lehrgang 1.U.L.D., Pillau. (U-Boat Training Course in 1st U-boat Training Division, Pillau.) |
| 01.10.1940-02.11.1940 | U.T.O-Lehrgang Torpedoschule, Flensburg-Mürwik. (Torpedos Training Course in the Torpedo School, Flensburg-Mürwik.) |
| 03.11.1940-24.11.1940 | U.W.O-Sperrlehrgang Sperrschule, Kiel-Wik. (Mining Course in Mine Warfare School, Kiel-Wik.) |
| 25.11.1940-21.12.1940 | U.W.O-Lehrgang Marine-Nachrichtenschule, Flensburg-Mürwik. (Communications Training Course in Naval Signals School, Flensburg-Mürwik.) |
| 22.12.1940-31.01.1941 | zur Verfügung Unterseebootsausbildungsabteilung, Plön in Holstein. (was attached to the U-boat Training Unit, Plön.) |
| 01.02.1941-13.03.1941 | zur Verfügung 2. U-Flottille, Lorient. (was attached to the 2nd U-Flotilla in Lorient.) |
| 14.03.1941-29.11.1941 | 1. WO auf 'U 103' [Kdt: Schütze später Kdt: Winter] / 2. U-Flottille, Lorient. Zwei Feindfahrten, 164 Seetage. (First Watch Officer. Completed two war patrols, 164 days at sea.) |
| 30.11.1941-07.01.1942 | KSL 24. U-Flottille, Memel. (U-Boat Commander Torpedo Shooting Course.) |
| 08.01.1942-21.04.1942 | zur Verfügung 2. Unterseebootsausbildungsabteilung, Neustadt i. H. (was attached to the 2nd U-boat Training Unit.) |
| 22.04.1942-31.05.1942 | zur Verfügung 2. U-Flottille, Lorient. (was attached to the 2nd U-Flotilla in Lorient.) |
| 01.06.1942-01.09.1943 | Kommandant auf 'U 66' / 2. U-Flottille, Lorient. Drei Feindfahrten, 325 Seetage. Das Boot abgebrochen Ein Feindfahrt wurde angegriffen von einem Flugzeuge von aus Nr. 172 Sqdn RAF und wurde schwer beschädigt und Rückkehr zum Lorient nach 3 Seetage. 5 Dampffrachtschiffe 26.610 BRT versenkt, 4 Motorfrachtschiffe 18.355 BRT versenkt, 2 Turbinentankern 20.358 BRT versenkt, 1 Dampftanker 8.621 BRT versenkt, 1 Motorfischerboot 113 BRT versenkt, 1 Turbinentanker 10.172 BRT beschädigt und 2 Motor-Torpedoboote 64 ts. beschädigt. (Commander. Kptlt. Friedrich Markworth takes command of U 66 from KK. Richard Zapp. Completed 3 patrols, 325 days at sea. One aborted patrol, 3 days, Kptlt. Friedrich Markworth was forced to return after the boat was depth charged by the British 'Wellington' aircraft from No. 172 Squadron RAF during the crossing of the Bay of Biscay to carry out a second patrol, during the last patrol under the command of Kptlt Markworthh U 66 was attacked by one Avenger aircraft and one Wildcat aircraft from VC-1 Sqdn. USN operating from the US escort carrier USS Card, Kptlt. Friedrich Markworth, the 1st WO and 7 other men were wounded and the 2nd WO was killed, three days later the U 117 transfer a WO as replacement Oblt. Paul Frerks from U 117 took temporary command of the boat and U 117 began refuelling the U 66, during fuel transfer the two boats was attacked by 'Avenger' aircraft from VC-1 Sqdn. USN operating from the US escort carrier USS Card U 66 managed to escape and was forced to return to base, arrive at Lorient after 147 days. Sunk 5 steam cargo ships 26.610 GRT, sunk 4 motor cargo ships 18.355 GRT, sunk 2 turbine tankers 20.358 GRT, sunk 1 steam tanker 8.621 GRT, sunk 1 motor fishing vessel 113 GRT, damaged 1 turbine tanker 10.172 GRT and damaged 2 motor torpedo boats 64 Dton.) |
| 02.09.1943-18.10.1943 | Schwer Verletzt Aufenthalt im Marinelazarett Lorient u. zur Verfügung 2. U-Flottille, Lorient. (Seriously Wounded and Hospitalised in Naval Hospital and was attached to the 2nd U-Flotilla in Lorient.) |
| 19.10.1943-22.02.1945 | Ausbildungsoffizier 23. U-Flottille, Danzig. (Training Officer in the 23rd U-Flotilla, Danzig.) |
| 23.02.1945-08.05.1945 | zur Verfügung 25. U-Flottille, Travemünde. (was attached to the 25th U-Boat Flotilla in Travemünde.) |
