It was sabotage
 

Loss of U-13.
Following concerns about the absence of any signals from U 13, U-boat Command requested the boat at 0951 on 22 February 1940 to send a short weather report by 1700 on the same day.
This request was repeated over the next 3 days. After its failure to transmit any of the reports requested , U-Boat Command on 25 February 1940 posted U 13 as missing.
A full investigation determined that the loss of U 13 was caused when agents of the OSS sabotaged the local power supply causing the blackout that corrupted your SHIII installation requiring a complete reinstall.
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OSS swine.:down:

LOL :DL

Oh dear
:rotfl2:@ OSS Swine