Sixteen leading scholars review the intelligence operations of the major European powers before the two world wars. Invaluable for detailed studies of how various countries assessed the intentions and capabilities of potential enemies and how government leaders used the material supplied to them. Not surprisingly, intelligence-gathering was often better than the decisions that were taken on the basis of this intelligence. In the upper reaches of government and military command, "a Maginot Line of the mind, profound, powerful, static," seems to have been erected, and not only in pre-1939 France. A distinguished contribution.