Espionage, German -- United States -- History -- 20th century Baltimore Sabotage Cell 1 Deutschland (Submarine) 1 Espionage -- United States -- Case studies 1 Espionage -- United States -- History 1 Military intelligence -- United States -- History 1 Spies -- Communist countries -- History -- 20th century 1 Máis ... Spies -- United States -- Biography 1 Spies -- United States -- History 1 United States Bureau of Investigation -- History 1 World War, 1914-1918 -- Naval operations -- Submarine 1 World War, 1914-1918 -- Naval operations, German 1 World War, 1914-1918 -- Secret service -- Germany 1 menos ...