Dr. Ralph Weber is a professor of history at Marquette University. He wrote this monograph while serving as scholar in residence at the Center for Cryptologic History from 1990 to 1991. Dr. Weber was also a scholar in residence at the Central Intelligence Agency from 1987 to 1988. He is the author of United States Diplomatic Codes and Ciphers, 1775 - 1938, published in 1979. In addition, he has written From the Foreign Press: Two Centuries of American History (1980); Final Memorandum: Ralph Van Deman, Father of American Military Intelligence (1988); Spymasters: Ten CIA Officers in Their Own Words (1999); and Talking with Harry: Candid Conversations with President Harry S. Truman (2001). Dr. Weber served in the U.S. Navy from 1944 to 1946.