In the rules it says that whenever a Shadow army enters the region where the entwood is, that army is attacked by the ents.
If a Shadow army attacks a FP army in a locality, in which also the entwood is, do you apply the Ents attack before or after the battle ? What I mean is : do you consider that the shadow army cannot enter the region until there is no more FP units in it ?
And if you apply the Ents attack once the Shadow army has won, do you consider that Shadow takes control of the locality even if they get wiped out by the Ents ?
The Ent attack doesn't occur until the Shadow Army actually moves into the Region that the Entwood is in, so the attack on the Free Peoples Army doesn't trigger it. The Ent attack would only be triggered if the Shadow Army won the battle and advanced into the Region afterward. If the Shadow Army is completely destroyed by the Ent attack, it does not take control of the Region, since control is taken at the end of an action.
"War is much more fun when you're winning!" - General Martok