My question is about the second edition, if it makes a difference.
From the Supply section:
A player is never allowed to take any action in the game that would cause him to exceed his actual supply limit as dictated by his position on the Supply track (such as mustering, marching or retreating, all explained later).
From the Mustering section:
A player may never muster a unit that would create or expand an army beyond his actual supply limit. In other words, if mustering a new unit would cause a player to have more (or larger) armies than allowed by his position on the Supply track, that unit cannot be mustered.
From the Combat/Retreat section:
A player may not retreat his defending units to an area containing friendly units if this would cause him to exceed his Supply limit. If a player’s only option is to retreat to such an area, he must first destroy as many retreating units as necessary to be compliant with his Supply limit after retreating to the area. After taking such losses, he may retreat the remaining units.
So, this all seems pretty cut and dry to me that I can't have more units in a region than would be allowed by supply unless I'm forced to by some situation, in which case I must immediately kill off units until I'm under the supply limit again.
But I'll ask my question anyway, which is: Since the game allows for scenarios in which you must kill units due to supply constraints, is there anything that suggests I can just simply sacrifice units?
For instance, if I wanted to turn an army of four (region A) into an army of three to allow an army of four to form elsewhere on the board (region B) I currently have to march one unit out of A to somewhere else and march a new unit into B; compare this to simply taking footman off the board from A and using a march to reinforce B.