12 June 1916|
|Died||2 April 1943
|Years of service||1934–43|
|Awards||Knight's Cross of the Iron Cross with Oak Leaves|
Mohr joined the Reichsmarine in 1934. After serving as first Watch Officer (second-in-command) to Georg-Wilhelm Schulz in U-124 on three patrols, in September 1941 he assumed command of the U-boat on six patrols, and sank 27 merchant ships, for a total of 129,292 GRT of Allied shipping.
On 25/26 September 1941 Mohr was part of a Wolfpack that attacked convoy HG 73. Mohr sank Empire Stream, Petrel and Lapwing and Siremalm. Rolf Mützelburg sank the steamer Cortes, for which Mohr has been wrongly credited.
On 24 November and 3 December 1941 Mohr sank the British light cruiser HMS Dunedin and the steamer Sagadahoc. On 14 March 1942 British Resource was sunk by Mohr and his crew. In March Mohr achieved a run of successes; Ceiba and Acme (17 March), Kassandra Louloudis and E.M. Clark (18 March), Papoose and W.E. Hutton (19 March), Esso Nashville and Atlantic Sun (21 March) and finally Naeco on 23 March completed the run. All but three were United States-owned vessels.
He sank four ships from Convoy ON 92 in May 1942; SS Empire Dell, Mount Parnes, Cristales and Llanover. On 9 June the Free French corvette Mimosa was engaged and sunk by U-124, the escort screen prevented Mohr from sinking any ships from Convoy ONS.100. Mohr persisted, and three nights later, on 12 June, he sank the 4,093grt British steamer Dartford. Six days later, Mohr picked up Convoy ONS.102 in the congested Atlantic shipping lanes. He accounted for the American cargo Seattle Spirit, which destroyed 5,627grt. Mohr's last success of the year came on 28 December, when U-124 torpedoed and sank the British ship Treworlas (4,692grt).
On 9 January 1943 Mohr intercepted the United States Navy Convoy TB-1. In a single action Mohr and his crew sank Broad Arrow (7,718grt), Birmingham City (6,194grt), Collingsworth (5,101grt) and the 4,554grt Minotaur; amounting to approximately 24,000 grts.
On 2 April 1943 Mohr sailed U-124 to intercept Convoy OS.45. He succeeded in penetrating the escort screen and sinking Gogra (5,190 grt) and Katha (4,357grt) in position  The escorts were alerted and began hunting the U-Boat. Mohr was killed when U-124 was detected, engaged and sunk with all hands about 500 km (270 nmi) west of Oporto, Portugal, by the British corvette HMS Stonecrop and the sloop HMS Black Swan..
- Spanish Cross in Bronze (6 June 1939)
- Memel Medal (26 October 1939)
- Iron Cross (1939) 2nd Class (29 November 1939) & 1st Class (4 May 1941)
- U-boat War Badge (1939) (4 May 1941)
- Knight's Cross of the Iron Cross with Oak Leaves
- Chronology of World War II 1939-1945 by Alessandro Giorgi
- Rohwer 1999, p. 67.
- Rohwer 1999, p. 72.
- Rohwer 1999, p. 85.
- Rohwer 1999, pp. 86-87.
- Rohwer 1999, p. 94.
- Rohwer 1999, p. 102.
- Rohwer 1999, p. 103.
- Rohwer 1999, p. 104.
- Rohwer 1983, p. 143 [first addition].
- Rohwer 1999, p. 145.
- Rohwer 1999, p. 161.
- Clay, Blair. Hitler's U-boat War: The hunted, 1942-1945, p. 207.
- Busch & Röll 2003, p. 203.
- Fellgiebel 2000, p. 314.
- Fellgiebel 2000, p. 65.
- Busch, Rainer; Röll, Hans-Joachim (2003). Der U-Boot-Krieg 1939–1945 — Die Ritterkreuzträger der U-Boot-Waffe von September 1939 bis Mai 1945 [The U-Boat War 1939–1945 — The Knight's Cross Bearers of the U-Boat Force from September 1939 to May 1945] (in German). Hamburg, Berlin, Bonn Germany: Verlag E.S. Mittler & Sohn. ISBN 978-3-8132-0515-2.
- Fellgiebel, Walther-Peer (2000) . Die Träger des Ritterkreuzes des Eisernen Kreuzes 1939–1945 — Die Inhaber der höchsten Auszeichnung des Zweiten Weltkrieges aller Wehrmachtteile [The Bearers of the Knight's Cross of the Iron Cross 1939–1945 — The Owners of the Highest Award of the Second World War of all Wehrmacht Branches] (in German). Friedberg, Germany: Podzun-Pallas. ISBN 978-3-7909-0284-6.
- Rohwer, Jürgen (1999). Axis submarine successes of World War Two: German, Italian, and Japanese submarine successes, 1939-1945. Greenhill Books. ISBN 978-1557500298.