In September 1941, as war with Japan was on the horizon and the United States was becoming more involved in the war in Europe, Admiral Leigh Noyes, Director of Naval Communications, wrote to Ada Comstock, president of Radcliffe College,[1] that the Navy was looking for female codebreakers. For over a year, the Navy had been quietly recruiting male intelligence officers from leading colleges and now was embarking on the same experiment with women. Noyes confided that the Navy wanted

Thus began the Navy's recruitment of women into a secret proctored correspondence course in elementary cryptanalysis. By late spring 1942, the first wave of women had completed the course and reported for duty in Washington, DC.

The US Army soon followed the Navy in recruiting college women. During World War II, the two services employed some twenty thousand codebreakers; about eleven thousand of whom were women (30). The contributions of these individuals have, till now, gone mostly unrecognized.[2] In Code Girls, author Liza Mundy[3] highlights the work and personal stories of many of these women. Using archived documents, oral histories, and her own interviews with surviving codebreakers, she describes how these women accepted an unexpected change in their lives to further the nation's war effort and, after the war, returned (or not) to their prewar career plans.

One of Mundy's interviewees, Ann Caracristi, was recruited as an Army codebreaker after graduating from Russell Sage College in 1942. The twenty-three-year-old became head of the Army's Japanese address research section at the Arlington Hall codebreaking station (339). She recalled that

The women were encouraged to leave after the war. "In at least one interview, [Caracristi] recalled hearing a 'here's your hat, what's your hurry speech,' in which she and her colleague were shooed out of government."[4] Caracristi did get work in advertising, but within a year returned to codebreaking. She joined a successor agency of Arlington Hall that in 1952 evolved into the National Security Agency (NSA). At the time of her retirement from NSA in 1982, she was deputy director, the highest-ranking civilian in the agency.[5]

One of Mundy's most prominent subjects is Dot Braden, a Virginia high school teacher recruited by the Army's Signal Intelligence Service. Beginning in October 1942, she worked at Arlington Hall breaking codes that enabled the US Navy to locate and sink Japanese merchant ships. Though many other female codebreakers are briefly mentioned, readers need not be too concerned about "keeping the characters straight" to grasp the book's overarching thesis.

Code Girls succeeds on two levels: first, it will appeal to a general audience with its engrossing account of American women codebreakers, whose achievments during the war we can all be grateful for, and whose postwar careers helped change the life expectations of many other women. Second, the book makes a serious scholarly contribution to the history of World War II codebreaking. Though, since the 1970s, many studies of the work done at Britain's Bletchley Park have been published, far less attention has been given to American codebreakers, more than half of whom were women.[6] One of the story lines in Code Girls concerns the female naval reservists (WAVES) who worked at the Naval Computing Machine Laboratory in Dayton, Ohio, and later at the Naval Communications Annex in Washington to build and operate cryptologic bombes (electro-mechanical devices) designed to attack the four-rotor Enigma.

Liza Mundy does not delve into the technical details of codebreaking methods per se; rather, she makes clear the critical value of the intelligence extracted from enciphered messages by female as well as male codebreakers, not only regarding major battles like the Coral Sea or Midway, but for the day-to-day operations of American commanders throughout the war.[7] In so doing she has corrected an egregious omission in the history of codebreaking during the Second World War.