Impassable terrain is any terrain that completely blocks movement. This includes rock spires, deep rivers, sheer cliffs and most buildings, as well as high linear obstacles such as castle walls and fortifications.

Impassable terrain cannot be crossed during the course of a battle – units must go around it. In addition, if it is not possible to align a charging unit to the enemy unit due to the presence of impassable terrain, the charging unit has made a disordered charge.