The history of espionage is far older than any of today's intelligence agencies, yet the long history of intelligence operations has been largely forgotten. The codebreakers at Bletchley Park, the most successful World War II intelligence agency, were completely unaware that their predecessors in earlier moments of national crisis had broken the codes of Napoleon during the Napoleonic wars and those of Spain before the Spanish Armada.

Those who do not understand past mistakes are likely to repeat them. Intelligence is a prime example. At the outbreak of World War I, the grasp of intelligence shown by US President Woodrow Wilson and British Prime Minister Herbert Asquith was not in the same class as that of George Washington during the Revolutionary War and leading eighteenth-century British statesmen.

In this book, distinguished historian Christopher Andrew recovers much of the lost intelligence history of the past three millennia—and shows its relevance today.