Thanks for that.
I have Tillessen's career data to the point where he relinquished command of U-516 in December 1944. All this is pretty straightforward stuff from www.uboat.net and www.ubootwaffe.net
He is then said to have been transferred to command of a midget submarine flotilla and base until May 1945. I have Helmut Blocksdorf's history of the operations of the Kommando der Kleinkampfverbande (K-Verband) ('HITLER'S SECRET COMMANDOS'), but Tillessen's name is not mentioned at all.
Did he command a flotilla? Or did he serve in the K-Verband in a central staff role?
All very mysterious.

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