Quote Originally Posted by Sentinel
If the human player did this and exited before any combat took place you would automatically loose a big chunk of your force.
If you quit the battle (Esc - Exit battle), yes, you can expect unexpected results , and possibly unrealistic loses. But if you orderly withdraw from the battlefield (assuming that AI doesn't catch you with cavalry or whatever), you won't lose a single soldier.

Not that I have a habit to retreat...

While I'm also frustrated when the AI flees from the battlefield, instead of falling into my trap and getting destroyed, I'm glad that to see AI making a tactically wise move. Because, a soldier who runs away will be able to fight tomorrow.