Secret service Underground movements World War, 1939-1945 14 History 11 War 8 Aerial operations, American 3 Aerial operations, British 3 more ... Air pilots, Military 3 Campaigns 3 Escapes 3 Flight crews 3 American 2 Americans 2 Anti-Nazi movement 2 British 2 English teachers 2 Executions and executioners 2 Guerrillas 2 Kidnapping, 1944 2 Military operations, Aerial 2 Special forces (Military science) 2 Special operations (Military science) 2 Women 2 Commando operations 1 Cryptography 1 Diplomatic history 1 Diplomatic relations 1 Electronic intelligence 1 Espionage 1 Espionage, British 1 less ...