Usually the stone walls take no damage from grenadiers. But if a unit/animal/building is immediately near or on the stone wall and is attacked by the Gernadians, the stone wall will take indirect damage and can be broken. When attacking stone towers in the stone wall, the stone wall also takes on indirect damage when the genadiers attack and can therefore also be indirectly destroyed here.
Usually the stone walls take no damage from grenadiers. But if a unit/animal/building is immediately near or on the stone wall and is attacked by the Gernadians, the stone wall will take indirect damage and can be broken. When attacking stone towers in the stone wall, the stone wall also takes on indirect damage when the genadiers attack and can therefore also be indirectly destroyed here.