The book Invisible Armies presents a completely original narrative of war, demonstrating that, far from being an exception, loosely organized guerrilla warfare or insurgency has been the dominant form of military conflict throughout history.

Max Boot, a journalist and military affairs historian for the New York Times, traces guerrilla warfare and terrorism from antiquity to the present, recounting nearly thirty centuries of unconventional military conflicts.

With dramatic analysis of strategy and tactics, as well as a multitude of unforgettable characters — from Italian nationalist Giuseppe Garibaldi to the "Silent American" Edward Landsdale — Invisible Armies is "a reminder to politicians and strategists of the hard-earned lessons of history."