Operation Fortitude was the ingenious web of deception spun by the Allies to mislead the Nazis as to how and where the D-Day landings were to be mounted. 'One of the most creative intelligence operations of all time' – Kim Philby The story of how this web was woven is one of intrigue, personal drama, ground-breaking techniques, internal resistance, and good fortune. It is a tale of double agents, black radio broadcasts, phantom armies, 'Ultra' decrypts, and dummy parachute drops. These diverse tactics were intended to come together to create a single narrative so compelling that it would convince Adolf Hitler of its authenticity. Operation Fortitude was intended to create the false impression that the Normandy landings were merely a feint to disguise a massive forthcoming invasion by this American force in the Pas de Calais. In other words, the success of D-Day – the beginning of the end of the Second World War – was made possible by the efforts of men and women who were not present on the Normandy beaches. Men such as Juan Pujol, a Spanish double-agent (code-name GARBO) who sent hundreds of wireless messages from London to Madrid in the build-up to D-Day relaying supposed intelligence from his fictitious spy network. This allowed the enemy to conclude that the number of Allied divisions preparing to invade was twice the actual number. Men such as R.V Jones, the head of British Scientific Intelligence, who masterminded the dropping of tinfoil confetti from the bomb-bay doors of Lancaster bombers, creating a false impression that a flotilla of Allied ships was heading in the opposite direction to the genuine invasion fleet. Using first hand sources from a wide range of archives, government documents, letters and memos Operation Fortitude builds a picture of what wartime Britain was like, as well as the immense pressure these men and women were working under and insure D-Day succeeded.