Also when a Corps or Army is disbanded due to casualties, you need to take the Commander as a casualty first, otherwise he will keep giving his bonus.
You can then use edit in NCM to swap him out with any surviving unit that was under his command if needed.
You don’t need to fight the battle in edit usually in that case. Mostly it’s for big battles or Paratrooper combined with Air attacks as it won’t let you retreat the Air until all the Paras are dead.
LM attacks as well. That way you don’t have to undo the move and redo if any hits. You can just kill them in the first rd and not count any hits the dead guys get