Files W.F.F. Archive Correspondence, Memoranda, and Personnel File Records Correspondence Found by William Friedman In 1947. the Correspondence Is Between Colonel Mauborgne and George Fabyan (1917-1919) Which Was Forwarded by Fabyan to Brigadier General M. Churchill (1919), Director of Military Intelligence. Subject of Correspondence Covers the at and T Cipher Machine, Riverbank Laboratories, and Running Key Ciphers. Friedman Inserted Margin Notes Commenting on Content, 1919-1947