Secret service World War, 1939-1945 56 History 33 Intelligence service 15 Spies 15 Military intelligence 11 Biography 10 Cryptography 7 Espionage 6 World war, 1939-1945 5 Campaigns 4 Politics and government 4 Underground movements 4 Cold War 3 Foreign relations 3 Great Britain 3 Personal narratives, British 3 United States 3 Commando troops 2 Deception 2 Espionage, Germany 2 Espionage, Japanese 2 Germany 2 Japanese 2 Malaya 2 Personal narratives, American 2 Police 2 Relations 2 World War 2 World war 2