I'm a little worried about what posture to put besieging units into. If I put them into a defensive stance the units I'm besiging would be free to walk out of the structure - or relieving forces to walk in without impediment I think?
If I put them into an aggressive posture I would be the one to lose defensive advantage if a relieving force entered the region in a defensive posture or if the structure defenders decided to sally forth (but in a defensive stance) This all seems a little odd.
It also made me think about the siege of fort Schulyer and the fact that a combined irregular and milita/regular force were able to execute an ambush :-
"The Tories chose an ambush point 6 miles east of Fort Schuyler, not far from the Oneida village of Oriska. Dense virgin forest provided excellent concealment for forces around a ravine where an old military road descended to cross marshy little Oriska Creek. Butler's Rangers and Johnson's Greens were deployed to hit the head of the column while the Indians attacked the flanks and rear. The idea was to surround the column in a U-shaped pocket and close the open end of the trap."
It seems that in BoA only lone irregular forces are able to set an ambush. Maybe a combined force should also have this option?
Cheers, Chris