A transfer or not
 

Got a quick question here, First off, I'm playing a "Med" career with the 23rd/29th Flotilla's, out of Salamis. It was on May 3, 1942 when I received a radio message, from BDU to U-81. "U-81 (that's me) The Base Was Changed To: LaSpezia. Have I been transferred to LaSpezia or is the just a general radio message ? My mission orders still says to return to Salamis. Thanx

In this case I would say your base has definitely been changed. The general messages are almost always news reports of one form or another.

Yes, historically the flotilla you are currently in was transferred to La Spezia in May 1942 so you should end your patrol there. I think if you saved and exited the game now then reloaded it, your mission orders would be updated too in accordance with the radio message.