Arlington author Liza Mundy will talk about her most recent book, “Code Girls: The Untold Story of the American Women Code Breakers of World War II,” at the Pohick Regional Library on Sept. 12 starting 7 p.m.

Mundy wrote about a group of women who worked on the then top secret Venona Project, a counter intelligence program started by the U.S. Army’s Signal Intelligence Service (SIS), that started during World War II.

More than 10,000 codebreaking women were instrumental in deciphering encrypted messages, some of which were Japanese and Soviet. This led to the arrest of several spies like Americans Julius and Ethel Rosenberg, British intelligence officer Kim Philby, British diplomat Donald Maclean, and the German physicist Klaus Fuchs.

Mundy describes some of these women — Angeline Nanni, Gloria Forbes, Mildred Hayes, Carrie Berry, Jo Miller Deafenbaugh, Joan Malone Callahan, Gene Grabeel — and their lives and what they did to aid the development of computers, code-breaking and cybersecurity. Mundy dispels the notion that women held unimportant roles during the war, and that they in fact did most of the codebreaking work in the Venona project.

Mundy first learned the stories of these women from a declassified Venona 1995 file written by National Security Agency (NSA) historian, Robert L. Benson. He wrote that most of the members of the cryptanalytic unit of SIS, the precursor to the NSA, were women, and he was able to interview a few of them.

Based on Benson’s article, Mundy reviewed rosters, reached out to family members identified by the NSA and requested alumnae records from colleges like Goucher and Wellesley. That wasn’t Mundy’s only challenge; once she found these women she also had to convince the surviving members of the group to share their stories, because even though the information was declassified, the women still felt they shouldn’t talk about their work that was considered confidential for a long time.

These women moved to Washington, D.C. to work at the SIS offices in Arlington. They worked in Arlington Hall, a building that is now on the National Register of Historic Places. The 100-acre Arlington Hall Station is presently the Department of State Foreign Service Institute. Located at the corner of South George Mason Drive and Arlington Boulevard, the former girls school, Arlington Hall Junior College for Girls, became the headquarters of the codebreakers during World War II. By coincidence, Mundy’s home is a few minutes away from Arlington Hall.

“Code Figures” is a new addition to books written about the little known but important work of women that started during World War II like “Hidden Figures: The American Dream and the Untold Story of the Black Women Mathematicians Who Helped Win the Space Race” by Margot Lee Shetterly, and “Rise of the Rocket Girls: The Women Who Propelled Us, from Missiles to the Moon to Mars” by Nathalia Holt.

Mundy, a former Washington Post writer and currently a senior fellow at New America, has written extensively about women including “The Richer Sex,” “Michelle” (a biography of First Lady Michelle Obama), “Why is Silicon Valley So Awful to Women,” “Playing the Granny Card,” “Wendy Davis, the Most Judged Woman in America,” “Monica Lewinsky Reconsidered,” “The Secret History of the Women in the Senate,” “The New Power Wives of Capitol Hill,” “Maternal Truths,” among other articles and essays.