Madame X by Mireille D'aureville

Agnes Meyer Driscoll was one of the most important American codebreakers of the twentieth century, yet for decades her name remained hidden behind secrecy, bureaucracy, and the men who became famous after learning from her.

Known inside cryptologic circles as “Madame X” and “Miss Aggie,” Driscoll worked across World War I, the interwar years, World War II, and the early national-security era. She broke or helped break major Japanese naval systems, trained future leaders of U.S. naval intelligence, tested cryptographic machines, and helped build the foundation of American naval cryptology long before the NSA existed.

This biography tells the story of Driscoll as more than a brilliant woman solving puzzles in a secret room. She was a teacher, analyst, inventor, machine tester, Navy pioneer, and bridge between old paper-and-pencil codebreaking and the rise of modern signals intelligence. Her work against Japanese naval codes before World War II helped create the intelligence foundation later used in the Pacific War, yet the institution she served rarely gave her power equal to her knowledge.

Madame X follows Driscoll from her early training in mathematics, physics, music, and language to the Navy code rooms of Washington, the breaking of Japanese Red Book and Blue Book systems, the struggle against JN-25, and the transition into the machine age of cryptology. It also tells the harder story: injury, rivalry, failure, transfer, sexism, secrecy, and late-career erasure.

Agnes Meyer Driscoll did not command a fleet or stand on the bridge at Midway. But before ships could be found, messages had to be read. And before messages could be read, someone had to believe the numbers were speaking.