Secret service History 56 World War, 1939-1945 45 Spies 34 Espionage 31 Espionage, German 17 Espionage, British 14 more ... Intelligence service 12 Military intelligence 10 Espionage, American 9 Foreign relations 7 Cold War 5 Espionage, Soviet 5 Subversive activities 5 Underground movements 4 Autonomy and independence movements 3 Neutrality 3 Police 3 World War, 1914-1918 3 Anti-Nazi movement 2 Collaborationists 2 Cryptography 2 Diplomatic history 2 Espionage, Japanese 2 Jewish refugees 2 Jews 2 National security 2 Naval operations 2 Officers 2 Participation, Jewish 2 less ...