NSA celebrates Armed Forces Week with a look at a U.S. Army cryptologic achievement.

In the years immediately preceding America's entry into World War I, the Army took its first steps into the world of cryptology. A young Army officer, Captain Parker Hitt, became interested in the subject while attending school at Fort Leavenworth, Kansas. After identifying issues within the Signal Corps cipher desk, he turned his attention to code solution. He later published the Manual for Solution of Military Ciphers, the first book devoted to cryptology ever published in the U.S.