Some units are so ferocious in close combat that they will rampage through enemy forces in a berserk fury, heedless of their own safety.
Where your unit has the Rampage ability:
When you roll for hits in close combat, roll two dice to score hits with this unit rather than the usual one die.
While the unit is in base contact with an enemy unit, it cannot make a Retreat move. This means that if you lose a close combat while you have Rampage units in base contact with the enemy, these units are always caught and destroyed by the enemy. Make the Retreat move with other units in the detachment as normal.