Quote Originally Posted by A Very Super Market View Post
Well, FMs need the "Forager" trait in order to do so.
No they don't.The game seems to decide at random if your army is in supply.
Sometimes an army is out of supply the turn after moving them into enemy territory and other times its in supply for a 3 year siege.

It really becomes apparent when you move a general from a siege and two seasons later they are getting negative morale modifiers despite being in a type1 city.

Supply is broken.