Since ancient times, individual radicals, disadvantaged groups, and angry populations under occupation have resorted to terrorism and guerrilla warfare as the only military means available when facing stronger conventional forces. Hiding in the shadows and emerging to attack where they are least expected, they seek to cause enough pain to persuade their enemies to give up. Boot’s coverage is remarkably comprehensive, taking in revolutionary movements and anticolonial resistance campaigns, special forces working behind enemy lines and large-scale counterinsurgency operations, the revolts of Bar Kokhba and Robert the Bruce, the political violence of John Brown and that of the Ku Klux Klan, and charismatic guerrillas such as T. E. Lawrence and Che Guevara. Boot sustains the reader’s interest with lively writing and sharp characterizations, including detailed riffs on the personal hygiene and sex lives of guerrillas. His conclusions confirm that although guerrillas, insurgents, and terrorists have had their successes, the strong normally prevail over the weak. Invisible armies work best when they are able to build up visible political support and link up with (or become) even more visible conventional forces.