Here is a link to a
fairly complete sequence of events in turn processing.
http://dom3.servegame.com/wiki/Turn_resolution
Dom3 is very sequential. Basically, it doesnt tend to back up and rethink anything. So much is decided by the order of processing, which nation is processed first, the ID order of units, etc etc.
It also tends to do very little storage of into between turns which tends to answer many other questions about "why doesnt this work".