Intelligence is the hidden force behind many major events in world history. The Cold War spying game, as depicted by John le Carré, has been going on for centuries. Almost every devious trick used by the KGB or the CIA would have been familiar to Francis Walsingham, Queen Elizabeth I's intelligence chief. Secret intelligence connections have been key to the success of all the great statesmen and generals from Caesar and Genghis Khan to Cardinal Richelieu and George Washington.
Today, with radio, telephone and email, intelligence has been transformed and vast agencies spawned by the world wars and the Cold War have now reinvented themselves for the `war on terror' : a war that can only be won by intelligence, in all its forms.