The code breakers of Room 40;: The story of Admiral Sir William Hall, genius of British counter-intelligence

Cloth; Very Good; Dust Jacket - Good; Blue cloth binding, Green illus. dj, some wear, sl. soil. frontis., 212pp. incl index., illus. The Story of Admiral Sir William R. Hall, Genius of British Counter-Espionage who cracked the German secret code. The Zimmermann tellegram was decoded by Hall. A very nice copy.