Question:
If a unit tries to ship to Malta and fails the roll, is it done with movement? Or can it continue to move from the port by road, rail, or another port? (assuming sufficient MPs remaining)
Answer:
Rule 28D (and Rule 26C, which Rule 28D draws upon for the turn-back result), places no special restrictions on the unit that was turned backed, except that the unit cannot attempt to ship to the destination again that turn (28D says that it can try in future turns, which I also read as meaning it cannot try again in the current turn). So, an Allied unit could move to a port like Alexandria, attempt to ship to Malta at a cost of 2 MPs, be turned back, and then use its remaining MPs to move elsewhere.
Historically, this would amount to something like: the high command orders the unit to Malta, but Axis air and naval interference causes the transports to turn back. When they arrive back at port, the high command has decided that the military situation now requires the unit to be used elsewhere.
Source:
Posted by John Astell on the Yahoo Classic Europa mailing list on 27.01.2013 17:34

