Most of the great military campaigns and breakthroughs of World War II would not have been successful without the efforts of teams of people working unsung and undercover. The codebreakers of Bletchley Park cracked codes that allowed for the interception and exploitation of German intelligence but many took the secret of their wartime activities to the grave. Others put their lives on the line to gather information for their countries, infiltrating other nations' secrets at great personal risk.This fascinating book covers some of the main campaigns carried out by the secret services such as the fabled Operation Mincemeat, and others, such as Operation Fortitude, carried out in support of D-Day. It also looks at the case of the fifth columnists and stories of double agents such as Agent GARBO.