In a dedicated end-of-turn phase any unit may deliberately withdraw 12" while staying faced to the enemy, at the cost of its next operation.
How it works
In phase 15 any unit, even prone or one that has used both operations, may fall back the full 12" to its rear without moving closer to the enemy or through units (unless skirmishers). It must first pass a morale test, ends facing the enemy, and loses its first operation next turn (guns must unlimber again). Non-skirmish units falling back cause morale checks on friends within 4".
During phase 15 of the Sequence of Play, all units (including those in a prone formation) may make a Voluntary Fallback of 12" to their rear.