Much of this information, the data, the photos etc. comes directly from the veterans, the veterans' organizations and is the most accurate available anywhere..............much of this information is not even known elsewhere.

II-B Deutsches Werft (Kiel) 28 Aug 1936
24 Sep 1936 and again
  3 June 1943
M02984 10 Sep 1944
her crew off Turkish coast unknown

             No men lost

Commanders of U-23 include:

KRETSCHMER OTTO Kplt Sep 1938 23 Mar 1940 U-99 POW from U-99
Beduhn Heinz Kplt 23 Mar 1940 Mar 1942 U-25 KIA aboard U-25
Wahlen Rolf-Birger Kplt Mar 1942   U-2514 and U-2541  
Reichenberg-Klinke Kurt Kplt     U-217 KIA aboard U-217
Driver Heinrich Kplt     U-20, U-145 and U-371  
Bruller   Kplt     U- 7 and U-407  
Graf Ulrich       U-69 KIA aboard U-69
Ahrend Rudolf Oblt zS     U-18  
KRETSCHMER (122-1985) Heinrich Driver  

NOTE - Sharkhunters Member's names appear in bold capital letters followed by their Membership Number..

U-23 finished up maneuvers over 13 to 23 September 1939 then she was attached as a Frontboot (combat boat) attached to the U-Bootflottille Weddigen then transferred to the 1st U-Bootflottille in Kiel.  She undertook three Feindfahrten (war patrols) in the North Sea.  She covered Northeastern Scotland September 1939 and February 1940 then in the area of the Orkney and Shetland Islands over December 1939 and January 1940, laid mines in Cromarty Firth on 4 November 1939.

No one else is aware that U-23 under OTTO KRETSCHMER (122-1985) was ready to sail into Scapa Flow and attack the battleship HMS ROYAL OAK.  He was quite angry when he and the other Type II-B boats in the North Sea were ordered to stand away from the Orkney Islands to avoid making the Royal Navy aware that an effort was coming to sneak U-47 into the anchorage to sink the battleship.  KRETSCHMER knew nothing of this plan even though Günther Prien was a good friend AND it was KRETSCHMER's own brother, flying for the Luftwaffe, who did much of the aerial reconnaissance over Scapa Flow for Prien's mission.

Aerial photo of Scapa Flow (right)

U-23 was then assigned to the 21st U-Bootflottille based at Pillau where she was a Schulboot (school boat).  Later U-23 was decommissioned and disassembled, transported via autobahn and rivers to Romania where she was rebuilt and recommissioned in the 30th U-Bootflottille and operated out of Costanzia, Romania against Soviet forces based in the Black Sea.

                  SHIPS SUNK BY U-23 (KRETSCHMER commanding)

   4 Oct 1939 GLEN FARG England Freighter      876 tons
   8 Dec 1939 SCOTIA Denmark Freighter   2,400 tons
   9 Dec 1939 unknown unknown unknown   2,500 tons est.
11 Jan 1940 FREDVILLE Norway Freighter   1,150 tons
12 Jan 1940 DANMARK Denmark Tanker 10,517 tons
24 Jan 1940 BISP Norway Freighter   1,000 tons
18 Feb 1940 HMS DARING England Destroyer   1,375 tons
22 Feb 1940 LOCH MADDY England Freighter   4,996 tons
HMS DARING LOCH MADDY bow (sinking) LOCH MADDY stern (salved)

LOCH MADDY was initially torpedoed by U-57 (Korth) and abandoned.  U-23 hit her again and she broke apart.

SPECIAL NOTE; MORE INFORMATION - There is much more information on this boat and others in our book "The Rare Types".   CLICK HERE for more information on this boat.

SHIPS SUNK BY U-23 (Wahlen commanding)

24 Aug 1943 SC-207 Soviet Mine sweeper    586 tons
15 Oct 1943 unknown Soviet unknown 2,000 tons
23 Oct 1943 unknown Soviet Freighter 1,000 tons
23 Oct 1943 unknown  * Soviet Fishing boat unknown
?? Jan 1944 unknown Soviet Freighter 1,500 tons
?? Jan 1944 unknown Soviet Tanker 2,000 tons
  5 Apr 1944 unknown   ** Soviet Minesweeper unknown
29 May 1944 unknown   *** Soviet Tanker 1,800 tons
  2 June 1944 unknown   **** Soviet Fishing boat unknown
  3 June 1944 unknown Soviet Gunboat unknown

   *       Fishing boat sunk by gunfire;
**      Minesweeper sunk by gunfire
***    The tanker was beached when U-23 hit her with one more torpedo;
****  Fishing boat sunk with hand grenades; they took three prisoners.

                  SHIPS DAMAGED BY U-23 (Ahrendt commanding)

   Sep 1944 OITUZ Soviet Freighter 2,686 tons

Ahrendt fired three torpedoes into Costanzia Harbor through the nets and reported two detonations near the dock of the Romanian destroyer REGELE FERDINAND and one detonation near a 6,000 ton freighter.  Actually only OITUZ was hit and damaged but she was already damaged and this torpedo caused her to be a total loss.  The other torpedo hit a dock and damaged it.
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Many thanks to our friend and Sharkhunters Member since 1987 GEORG HÖGEL for all the conning tower emblems used in our monthly KTB Magazine and also here on the pages of our website.  GEORG was radioman aboard U-30, the first boat into combat, the first to sink a ship (the liner ATHENIA) and the first into an occupied French port.  When that Skipper (Lemp) took command of U-110, GEORG was one of the former crew to transfer to the new boat under Lemp.  After the war, he was Professor of Art at a major German university.