In his book Marketing Warfare, Al Ries equates marketing to war. Marketers can't just target their customers, they must attack their competition and be prepared to defend their turf from would be attackers at all times.
The word strategy originally referred to military strategy. In ancient Athens, strategus was the highest ranking military commander and a member of the Council of War. The word strategy originates from Greek words stratos (army) and agein (to lead). Today strategy can mean any long term plan of action designed to achieve a particular goal, usually involving some type of adversary.