Any units that do not rally must immediately flee 2D6" in the direction they are facing. Every model that flees through an enemy unit or impassable terrain must take atest.
If, despite the player's best efforts, a unit continues to flee, it will continue its headlong flight for safety, moving 2D6" straight ahead in the direction it is facing. Some particularly swift units flee faster, but we'll discuss those later on.
As fleeing troops are assumed to have broken formation, they ignore obstacles of any kind as they retreat. Fleeing troops move through other units (friend or foe) and impassable terrain, as they are assumed to run around the obstruction, or force their way through, fuelled as they are by sheer desperation. If the flee move would result in the fleeing unit ending up 'on top' of or within 1" of another unit or impassable terrain, then it carries on fleeing straight forward until it is past the obstruction, and will then halt.
Fleeing through enemies or impassable terrain is not without its dangers. Enemies may be quick-witted enough to capture or slay several of the fleeing troops as they run past, while the sheer drops, deep water and dense undergrowth of impassable terrain present all kinds of hazards to a warrior more concerned about what he is running from than what he is running into. Accordingly, each fleeing model must pass a Dangerous Terrain test for each enemy unit or area of impassable terrain that it flees through. More information on Dangerous Terrain tests and impassable terrain can be found in the Battlefield Terrain chapter.
There are consequences for a unit fleeing through friends as well – having allies stream past you in a panicked state is not conducive to maintaining your confidence in victory, after all! Any unit that has friends flee through it must take a Panic test (as described in the Panic chapter), as soon as the fleeing unit has completed its move.
As soon as a fleeing unit moves into base contact with the battlefield edge, it flees the battle and does not return – we assume that its warriors scatter to the four winds. Such a unit counts as destroyed to all intents and, more importantly, all rules purposes.