From the back of the book:Battlegroup is a set of tabletop wargame rules for recreating the battles of World War II with 20mm or 15mm miniatures.This is a core rulebook detailing how to play the game including such basic rules as Command and Control Movement Firing and Morale.Command and Control: The rules use a system of Orders putting difficult tactical decision making in the centre of the game.Firing: A unique 'two-tier' system for firing involves Area fire and Aimed Fire in which pinning enemy units can be as important as destroying them.Morale: The innovative Battle Rating counters system means no two game will ever play the same.To play you will also need a collection of wargames miniatures a wargames table an opponent and one of the Battlegroup Theatre supplements which provide all the detail army lists and character of specific battlefields and periods of war.