This attack may be used by units containing models with Sweeping Attack.
When the unit Advance Moves or March Moves, you may nominate a single unengaged enemy unit that the unit with Sweeping Attack moved through or over during this move (meaning their bases were overlapping, even partially).
The whole unit makes the Sweeping Attack against the nominated enemy unit, which is resolved when the March or Advance Move is completed. Follow the description in the unit profile.
These attacks hit automatically and count as ranged Special Attacks. Each Sweeping
Attack can only be performed once per Player Turn.