Charging Through Difficult Terrain
Models are slowed when charging through difficult terrain. If, when charging, one or
more models have to move through difficult terrain in order to reach the enemy by the
shortest possible route, the entire unit subtracts 2 from its total when determining its
charge range. If at least one model in the charging unit moved through difficult terrain as
part of its charge move, all of the unit’s models must attack at Initiative step 1, regardless
of other Initiative modifiers, even if the charging unit is not slowed by difficult terrain.
Remember that charging models must engage as many enemies in the target unit as
possible.
My version of the rulebook has it stated :S