Throughout history, war has changed its face and developed into a myriad of manifestations. Therefore, also the classifications of warfare and the theories to win war had to adapt to those changes. One of the most recent theories revolves around the phemen the world faces today with warfare waged by terrorists and insurgents. The fourth generation warfare (4GW) model is still young and evolving and one cant find it in official documents of the Department of Defense (DoD). However, already it has established itself more and more in the writings of today's military theorists. In this paper, this author will give a brief summary of the most common existing models of warfare and highlight certain characteristics and strategies exploited and followed by the players employing 4GW. Two theorists, John A. Warden III and John R. Boyd shaped modern airpower. From Operation DESERT STORM to Operation IRAQI FREEDOM (OIF), their names are featured prominently in a number of analyses, books and articles. The US forces proved that their theories are valid when applied by a modern military force in a maneuver war waged with precision weapons. Nevertheless, one will define those operations as third generation warfare (3GW) and the validity of the theories in the Global War on Terrorism (GWOT), which is widely fought by terrorists as 4GW is still to prove. This paper will give a short summary of the two theories and then explicitly investigate the validity of the two theories in 4GW.