US term for a compendium of authoritative tactical and operational concepts intended for use especially by junior and field-grade officers. Field manuals proliferated in the era of the world wars, when, for the first time, vast armies of literate conscripts faced each other. They are the ‘Book’ against whose precepts soldiers proverbially rebel, but without which modern war would be impossible. Their scope and detail have lately become daunting, belying their original purpose as distillations of experience: the US army currently employs over 400 field manuals. Most are available on the World Wide Web.
Field manuals seek to represent the state of the art of war at any given moment. Their evolution is accordingly an index of intellectual and institutional change. One such bell-wether has been the US army's FM 100-5, Operations, which first appeared in 1939, and is now undergoing its twelfth revision. Along the way, FM 100-5 has registered and codified every perturbation in the American approach to war, including the advent of tactical nuclear weapons in the 1950s; ‘flexible response’ and ‘active defense’ in the 1960s; and ‘AirLand battle’ in the 1970s, a form of aggressive, high-speed manoeuvre warfare whose influence was apparent in the conduct of the Gulf war (1990-1). The new edition is again a reflection of changing times: its aim is to integrate the conduct of ‘operations other than war’ into the mainstream of army doctrine.
— Daniel Moran
