ASS-Datensatz 24416a und 24503

[TW]

Axis Submarine Successes Update --  Frans Beckers & Eric Zimmerman  --  May 2014

March 1943

26/0042  dt  U 431  CH8264    D 5000+  T  MKS.10  City of Perth  6415+  35.50N/01.41W  (6)
26/0043  dt  U 431  CH8264    D 6000=  T  MKS.10                                                               (6)
26/0044  dt  U 431  CH8264    D 8000=  T  MKS.10                                                               (6)

(6)  U 431 observed columns of smoke rising above the target after the first torpedo hit.  She heard two further detonations after 5 min 49 sec and 6 min and observed more columns of smoke.

27/1850  dt  U 77      Hartmann      CH7676    D    6000=    T    Unknown                              (2)

(2)  U 77 reported the torpedoing of one vessel in an eastbound convoy of 20 tall ships.

The Admiralty war diary for March 1943 states that the CITY OF PERTH was torpedoed from convoy MKS.10 at 1844/26th in position 35.47N  01.30W.  This position, as well as a second, 35.50N  01.41W is given by Lloyds War Losses.  The ship did not sink immediately but was taken in tow by the tug RESTIVE and beached near Cape Fegalo (west of Oran).  She became a total loss.  ADM 199/1785 indicates a counter attack by escort destroyers from convoy MKS-10, HMS ATHERSTONE and QUANTOCK assisted by the destroyer TARTAR.  These attacks took place following the torpedoing of the CITY OF PERTH, reported by ATHERSTONE at have occurred 1840A/26 and were between 1850A/26 and 1950A/26 in a mean position of 35.53N  01.40W.  They were clearly directed at the U-boat which torpedoed the CITY OF PERTH.

A summary of the KTB of U431 (OL Dietrich Schöneboom) for March 26, 1943 gives
0014 – CH8256 – surfaced.  0017 – Eastbound convoy in sight.  Attack from portside of the convoy.  0042 – 3 torpedo fan fired.  0043 – 1 torpedo (tube V) on big freighter, speed 10 knots.  0044 – torpedo fired (Tube II) on the same freighter.  0048 – One explosion on freighter 5000 tons, high smoke column.  Apparently ship is afire.  0049 – 2 explosions, two smoke columns of a 6-8000 ton freighter.  0055 – Diving.  0227 – Surfaced nothing more in sight.

Now dealing with the mass of information required to assemble a book like ASS it is easy to see how not every single entry could be examined at length.  Also information continues to surface but one thing is clear immediately clear when comparing German and Allied data.  The U431 did not sink the CITY OF PERTH.  The two incidents are separated by 18 hours and over 160 nautical miles.  Nor was there any counter attack recorded by U431 following the presumed torpedo hits and lastly MKS-10 was actually a westbound convoy.  There is presently no explanation as to what was attacked by U431 in the early hours of the 26th but it may have been the eastbound KMS-11 known to have been attacked in these waters by torpedo carrying aircraft from KG 26 early on March 26th during which the Dutch motor vessel PRINS WILLEM III was torpedoed at 0700/26 in position 37.00N  02.14E.  There is no indication found in any known Allied reports, that the attack by U431 was even noticed.

So what U-boat was responsible for torpedoing the CITY OF PERTH?  A clue can be found in ASS in the listing for U77 (OL Otto Hartmann).  This boat failed to return being lost over the night of March 28/29, 1943 following aircraft attacks, the primary damage being done by Hudson C/500 (Revised 02/2010 by Dr. Axel Niestlé and Eric Zimmerman).  Therefore no KTB exists but DEFE 3/714 (National Archives) holds intercepted and decrypted radio messages from both U431 and U77 during this time.  From U77 we find one with a TOO (time of origin) of 0558/27 which reports:  At 1850 torpedoed 6000 tonner in CH7676.  Forward periscope well not tight, multiple hydrophones out of order.  1 stern eel.  Request return passage.
The course of the convoy was not indicated in this signal nor was the cause of the damage to periscope and hydrophones but one can take the not very large leap to presume it was due to depth charging following the mentioned attack.  The date of the attack itself is not given but presumably it was the previous day to when the signal was sent i.e. the 26th, the time of 1850 is near an exact match for the Allied times given for the damage to the CITY OF PERTH.  It's not clear what data Professor Rowher used in entering the data on the attack by U77 but if it was the radio signals it would seem that the date of origin of the signal rather than the date it refers to was used for the entry.  A earlier signal from U77 on the 27th reports the sighting of an east bound convoy of 20 large ships but reports the sighting at 0130 in CCH7546.  This would of course refer to 0130/27th and thus although this signal originated earlier it refers to a later event.  Finally it is definitely worth noting that 35.50N  01.41W one of the positions given for the torpedoing of the CITY OF PERTH equates to CH7676, the exact position of U77's reported attack, while the other position and that given for the various depth charge attacks by escorts are all directly in this same area. 

It's abundantly clear that U77 was responsible for the loss of the CITY OF PERTH.

Sources
Axis Submarine Successes (ASS) – Jürgen Rohwer
KTB of U431 (courtesy Frans)
DEFE 3/714
ADM 199/1785
Admiralty War Diary - March 1943
Lloyds War Losses

[t-geronimo]

Schöne Aufklärungsarbeit!

Bravo Zulu! 

[ARANTALES]

Jawohl, schöne Aufklärungsarbeit von Eric und Frans.

Auch unser eigenes DUIKBOOT muss da korrigiert werden!!!
Das vorgestellte re-assessment betrifft nicht nur Axis Submarine Successes. ASS war hingegen eins der Quellen die zur Lösung führten, was spricht für den Wert dieser Quelle. 

Die nächste, korrigierte Aktualisierung von DUIKBOOT ist +/- beim Monatswechsel Mai/Juni vorgesehen. Bis dahin wird in DUIKBOOT die City of Perth angegriffen von U431...

Met vriendelijke groeten,
Frans & Walter