Fourth-generation warfare (4GW) is conflict characterized by a blurring of the distinction between war and politics, and of the distinction between combatants and civilians.
The term was first used in 1980 by a team of United States analysts, including William S. Lind, to describe warfare's return to a decentralized form. In terms of generational modern warfare, the fourth generation signifies the nation states' loss of their near-monopoly on combat forces, returning to modes of conflict common in pre-modern times.
The simplest definition includes any war in which one of the major participants is not a state but rather a violent non-state actor. Classical examples of this type of conflict, such as the slave uprising under Spartacus, predate the modern concept of warfare.
Fourth-generation warfare is defined as conflicts which involve the following elements:
Complex and long term
Terrorism (tactic)
A non-national or transnational base – highly decentralized
A direct attack on the enemy's culture, including genocidal acts against civilians.
All available pressures are used – political, economic, social and military
Occurs in low-intensity conflict, involving actors from all networks
Non-combatants are tactical dilemmas
Lack of hierarchy
Small in size, spread out network of communication and financial support
Use of insurgency tactics as subversion, terrorism and guerrilla tactics
Decentralised forces
The concept was first described by the authors William S. Lind, Colonel Keith Nightengale (US Army), Captain John F. Schmitt (USMC), Colonel Joseph W. Sutton (US Army), and Lieutenant Colonel Gary I. Wilson (USMCR) in a 1989 Marine Corps Gazette article titled "The Changing Face of War: Into the Fourth Generation". In 2006, the concept was expanded upon by USMC Colonel Thomas X. Hammes (Ret.) in his book, The Sling and The Stone.
The generations of warfare described by these authors are:
First generation: tactics of line and column; which developed in the age of the smoothbore musket.