Foreign Office Commander Mansfield Cumming “C”  Agadir Crisis  British Expeditionary Force  GHQ I(b) Admiral William Reginald “Blinker” Hall

NATURE OF THE GREAT WAR symmetric war timetable war consumer’s expectation cavalry as battlefield intelligence trench warfare static intelligence structures industrialized war of attrition (totalwar) war of ideologies

Margaret Zelle — Mata Hari Room 40

CRYPTOGRAPHY 101 plaintext steganography transmission security cryptography cipher transposition substitution cipher alphabets homophones nulls monoalphabetic cipher polyalphabetic cipher code code words monophone code  polyphone code digraph or bigram polygram encicode placode key keyword, keyphrase, or key number decipher or decode decrypt (verb) — cryptoanalysis decryption — decrypt (noun) cleartext or “in clear” or “in plain language” paradox of cryptanalysis

Arthur Zimmerman 

Zimmerman Telegraph (Zimmerman Note)