The ‘Code Girls’ of Arlington Hall Station: Women Cryptologists of the Second World War (Teaching with Historic Places)

Black and white image of women cryptologists at Arlington Hall Station in their desk doing work.
Women cryptologists at work at Arlington Hall Station in Arlington, Virginia.



The Signal Intelligence Service (SIS) was first founded in 1930. For most of WWII it was a part of the US Army Signal Corps. SIS grew rapidly, but men were needed for fighting overseas. To meet operational demands, recruitment shifted toward young women. By the end of the war, approximately 7,000 of the 10,500 SIS staff were female. These women on the home front contributed to the Allied victory by successfully breaking codes and deciphering enemy messages. The women cryptologists were held to strict secrecy and would become one of the best-kept secrets of WWII. This lesson shares the background of three of these women: Genevieve Grotjan Feinstein, Ada Stemple Nestor, and Ann Caracristi, who all were recruited and served for SIS at Arlington Hall Station. Each profile shares detailed accompanying source readings describing their time in service. The profiles of these three white women bring to life the incredible efforts conducted by thousands of home front women in secrecy in Arlington, Virginia during the war. Although African Americans comprised nearly 15% of the workforce, most of the women and their roles are poorly documented.


1) Identify contributions of women who served at Arlington Hall Station
2) Describe examples of both societal shifts and barriers on the home front of WWII, such as for women and African Americans
3) Create media that connects to and shares details about women cryptologists of WWII

About this Lesson
Includes authors, learning objectives, and materials for students
Getting Started: Essential Question
Photo 1: U.S. Army SIS cryptologists in Arlington Hall
Locating the Site
Photo 2: Arlington Hall: Main Building (1946)
Photo 3: Arlington Hall, aerial view
Map 1: Cutaway portion of Arlington, Virginia
Photo 4: Women in training courses at Arlington Hall
Photo 5:  African American special unit
Determining the Facts with readings and visual evidence
Reading 1: Genevieve Grotjan Feinstein (excerpt: Frank B. Rowlett: A personal profile)

Photo 6: Genevieve Grotjan Feinstein (Credit: NSA)

Photo 7: Genevieve Grotjan Feinstein receiving an exceptional civilian service award 

Reading 2: Ada Stemple Nestor (excerpt: “She Served her Country in Secrecy”)

Photo 8: ‘Code Girls,’ including Ada Nestor, at the National Mall

Photo 9: Certificate of Service, Ada Nestor, issued in 1945

Reading 3: Ann Caracristi (excerpt: Interview with Ann Caracristi)

Photo 10: Ann Caracristi in Arlington Hall

Photo 11: Ann Caracristi 

Optional Activities 
Activity 1: “The Invisible Cryptologists”
Activity 2: Creativity with Codes

Photo 12: Stamp designed by art director and designer Antonio Alcalá Credit:USPS

Activity 3: Cryptology Cartoons

Photo 12: Communications and Security; Crypto Chris posters

Photo 13: “Crypto Chris” cartoon


Arlington Hall Station is located in Arlington, Virginia, and is listed in the National Register of Historic Places. The site was first the location of Arlington Hall Junior College (established in 1927), and then the headquarters of the United States Army intelligence activities, from 1942 to 1989. Beginning in 1942, and through World War 2, it served as the headquarters of the U.S. Army’s Signal Intelligence Service (SIS). This was to expand from the smaller previous location (Munitions Building in Washington D.C.). Cryptography efforts in Washington D.C. were centered in the Naval Communications Annex and Arlington Hall. During the war, Arlington Hall became the largest message center in the world. The SIS developed codes and ciphers for the Army, produced cipher machines, and was responsible for cryptoanalysis of intercepted enemy messages. Japanese systems were often the focus at Arlington, including the encryption system known by the codename “Purple.” Several thousand women were recruited and had critical roles in the success of cryptology at Arlington Hall, playing a crucial role in the Allied victory. Today Arlington Hall is operated by the Department of State for use as a training center, as part of the 72-acre George P. Shultz National Foreign Affairs Training Center (NFATC). This lesson was authored by Sarah (Nestor) Lane, an educator currently located in Washington state. She is the granddaughter of Ada Stemple Nestor, who is profiled in this lesson. The lesson is one in a series that highlights women’s history and brings the important stories of historic places into classrooms across the country.

1)    Map 1, Photos 1-13: To display digitally (or print copies)
2)    Readings 1-3, with Questions
3)    Art supplies for optional activities 2 and 

Time period: World War 2
Topics: World War 2, women’s history, cryptology
United States History Standards for Grades 5-12
This lesson relates to the following National Standards for History from the UCLA National Center for History in the Schools:
Era 8: The Great Depression and World War II (1929-1945)
Standard 3: The causes and course of World War II, the character of the war at home and abroad, and its reshaping of the U.S. role in world affairs
Curriculum Standards for Social Studies
This lesson relates to the following Curriculum Standards themes for Social Studies from the National Council for the Social Studies:
Theme 2: Time, Continuity, and Change
Theme 5: Individuals, Groups, and Institutions 
Theme 8: Science, Technology, and Society
Theme 9: Global Connections
Relevant Common Core Standards 
This lesson relates to the following Common Core English and Language Arts Standards for History and Social Studies for middle and high school students:
Key Ideas and Details

Craft and Structure

Integration of Knowledge and Ideas

Range of Reading and Level of Text Complexity

Getting Started: Essential Question

How did women cryptologists support an Allied victory from the home front in WWII?

Photo 1: U.S. Army SIS Cryptologists in Arlington Hall (1943)

U.S. Army SIS cryptologists, in Arlington Hall, circa 1943
U.S. Army SIS cryptologists, in Arlington Hall, circa 1943.


Locating the Site
Photo 2: Arlington Hall: Main Building (1946)

Black and white photo of Arlington Hall, main building, dated 05/15/1946.
Arlington Hall, main building, dated 05/15/1946.

Library of Congress

Photo 3: Arlington Hall, aerial view

Aerial view of Arlington Hall today, State Dept. Training Center. There are buildings that connect to a main building and parking lots surrounding them.
Aerial view of Arlington Hall today, State Dept. Training Center.

Aerial View- Bing maps

Map 1: Cutaway portion of Arlington, Virginia

Bottom, Map 1: Arlington Hall, designated by a red star. Today the site is the National Foreign Affairs Training Center. On the map, Arlington National Cemetery and the Pentagon are to the east, and Washington D.C. is across the Potomac River.
Bottom, Map 1: Arlington Hall, designated by a red star. Today the site is the National Foreign Affairs Training Center. On the map, Arlington National Cemetery and the Pentagon are to the east, and Washington D.C. is across the Potomac River.

Arlington Country Virginia

Map 1 Questions
1. What factors may have contributed to the designated selection of the Junior College as a Military Intelligence site?
2. What limitations may there have been to recruit and house thousands to work at Arlington Hall?

Inside the Location: Arlington Hall (Photos 4, 5)

Women sitting in training courses at Arlington Hall
Women in training courses at Arlington Hall.


: "B" III Colonel Bearce, William Coffee in the background,” an African American special unit.
"B" III Colonel Bearce, William Coffee in the background,” an African American special unit.


Questions for Photos 4 and 5:
1. What do you notice about the classroom in photo 4?
2. What factors may have dictated the training environments at Arlington Hall? (ex. Time, spaces, security)
3. What challenges may the African American women in the special coding unit have faced in this role and in society at the time?

Determining the Facts
‘Code Girl’ Profiles
Reading 1:
Genevieve Grotjan Feinstein

Black and white portrait of Genevieve Grotjan Feinstein
Genevieve Grotjan Feinstein.


Genevieve Grotjan Feinstein receiving an exceptional civilian service award from Brig. Gen. P.E. Peabody in May 1946
Genevieve Grotjan Feinstein receiving an exceptional civilian service award from Brig. Gen. P.E. Peabody in May 1946.

National Archives

Bio: Genevieve Grotjan was born in 1913. She graduated from the University of Buffalo with a mathematics degree and was hired in 1939 as a junior cryptologist after her high score on a civil service mathematics test was discovered. Grotjan discovered a correlation among intercepted messages in 1940 after analyzing the encryption system used in the Japanese Machine. The SIS named its code “Purple.” Because of her discovery, SIS and the US Navy were able to build a “Purple” analog machine to help decode Japanese messages. Genevieve Grotjan married the chemist Hyman Feinstein in 1943. Genevieve Grotjan Feinstein passed in 2006 and was posthumously inducted into the NSA Hall of Honor (2010).

Excerpt from: Frank B. Rowlett: A personal profile, by Theodore Hannah

“Finally, Genevieve Grotjan finds the evidence we are looking for. Time is about 2 p.m. Ferner, Small, and I are at table in working area discussing prospects and reviewing work. Grotjan enters room, obviously excited, politely interrupts, asks if she can show us what she has found. She takes us to her desk in next room, lays out worksheets, points to one example, then another, then a third. She stands back, with eyes tranced behind her rimless glasses. Al Small dashes around the room, hands clasped above his head like a victorious prizefighter. ‘Whoopee!’ he yells. Ferner, the quiet one, clasps his hands, shouting “Hooray, Hooray.” I jump up and down – “That’s it! That’s it!” The room gets crowded; everyone in section suddenly in room. Friedman comes in and asks, “What’s all the noise about?”
I settle down and say, “Look what Miss Grotjan has just discovered.” Gene wipes her eyes, tries to regain her composure. I point to the worksheets – “Gene’s found what we’ve been looking for. Look here, and here, and here.” Friedman examines each one and understands what he sees; he looks suddenly tired. We take a break and send out for Cokes. The excitement gradually wears off and we look ahead to the next step.” – Frank Rowlett
That next step would soon lead to the solution of Japan’s highest level diplomatic cipher system, the so-called Type “B” machine, better known as “Purple.” What young, studious Genevieve Grotjan had discovered on that warm Friday afternoon in September 1940 represented the decisive breakthrough into a highly sophisticated machine system that for 18 months had stubbornly resisted the concerted attack by some of the best cryptanalysts in the world. Its solution has been called “the greatest feat of cryptanalysis the world had yet known,” one which, in the words of another author, “involved a unique intellectual effort of heroic proportions.”

Questions for Reading 1
1. What did Genevieve Grotjan successfully accomplish?

2. This event is described by Frank B. Rowlett, a cryptologist who helped lead the efforts in deciphering Japanese codes and systems. Do you believe his retelling of Grotjan’s accomplishment is significant? Why or why not?

3. What is “Purple” and its importance?

4. Consider the historical context of Genevieve’s accomplishments in September 1940. Why had cryptanalysis started before the United States’ formal entry into the war? (The U.S. entered in December 1941, after the attack on Pearl Harbor.)

Reading 2:
Ada Stemple Nestor

Ada Nestor (front right) and others from Arlington Hall at the National Mall, c. 1943
Ada Nestor (front right) and others from Arlington Hall at the National Mall, c. 1943.

Courtesy of the Nestor family

Ada Nestor, certificate of service from the Military Intelligence Division War Department, signed by, at the time, Major General Clayton Bissell, issued in 1945
Ada Nestor, certificate of service from the Military Intelligence Division War Department, signed by, at the time, Major General Clayton Bissell, issued in 1945.

Courtesy of the Nestor family

Bio: Ada (Stemple) Nestor was born in 1922. After graduating from high school in Barbour County, West Virginia, she attended Clarksburg Business College and was recruited by SIS. She served at Arlington Hall Station from 1942 – 1944. In 1944 she married Edwin Nestor, a Navy sailor. Ada was awarded a certificate of appreciation by the Library of Congress and Veterans History Project in March 2019, “for her service to and support of the nation as a World War 2 ‘Code Girl.’ Ada Nestor passed in August 2019.

Excerpt from: “She served her country in secrecy,” by Mandy Pfeifer

“I couldn’t believe what I had heard. I listened further. Again the newsman on the radio mentioned ‘Purple codes.’ I well knew the importance and the secrecy surrounding them. What surprised me so much to hear of them after so many years [recollection dates to the 1980s] was the fact that they were referred to as ‘Purple codes.’ I had been sure that was just the designation used in the office where I worked for the Military Intelligence Division of the War Department during World War 2.”
In 1941, when World War 2 started, Ada Nestor, at that time Ada Stemple, was still in college at Clarksburg West Virginia Business College. “No one believed, at that time, that any country would attack the United States. When they did, it was devastating,” Ada says.
It was in 1942 when Ada first took her job in Washington D.C. She had no idea what she would be doing. She was only told she would be working with numbers, and she would not be thrown into a typing pool.
At Arlington Hall Station, between Falls Church, Virginia and D.C., Ada found herself going back to school. From 8 a.m. to noon she attended courses in a combination of Geography / History, Morse Code, Radio, and Cryptology. “The classes were scary,” Ada recalls. “We had no books and weren’t allowed to take notes as nothing could be taken off the base. We had no time outside of class to study.” And although she was told it would never happen, from 1 p.m. to 5 p.m. she was thrown into a typing pool, typing five-digit letter coded messages.
Then one day, she was given her real job – identifying coded messages that were coming via teletype from over 20 receiving stations around the world, and then routing them to the proper decoders. “What I learned in class began to fall into place.” The teletype machines ran 24 hours a day and seven days a week. This meant dividing the working time into three different shifts. She would work the first shift for two weeks, then the second for two weeks, and then the third. It was an endless cycle.
Ada was not required to wear a uniform because the less attention drawn to the group the better. She lived in a home in Falls Church with a few other girls. Their home was not paid for by their employer, and they had no kitchen privileges. They were forced to eat out every night and their entertainment usually involved seeing a movie or learning about nursing, just as a precaution in case they were ever needed in that field . . . The buses often couldn’t pick up everyone because there were so many people in D.C., so people with cars were encouraged to pick up government workers. Ada and her friends were picked up one day by none other than Arthur Godfrey. [Radio and TV broadcasting personality of the period]
Ada and the other people in her job were told that ‘Purple codes’ had priority over all others. ‘Purple codes’ were Japanese codes . . . Japan had cipher machines, the machines that code messages, placed in seven embassies. It was the United States luck that our espionage agents had cracked the Japanese codes before the war even started. This allowed the United States to intercept and decipher Japanese codes without having to waste the time that is usually spent on figuring out the patterns.
“We had been taught that no secret is kept for long and no code so difficult that it wouldn’t eventually be broken. But Japan was sure their codes could not be broken, and they used these codes throughout the war,” Ada stated. It was important that the enemy didn’t find out the United States had cracked their codes, for if they did, the enemy would quickly change to a new code to throw the U.S. off course.
“It seemed they were telling us so much more than we needed to know. But we were a serious bunch. Everyone’s life had been turned upside down. So many lives lost – such a feeling of anger, not only at the enemy, but at ourselves too.” Ada couldn’t understand why the government was telling them the same thing they were telling the high-ranking officials. “Didn’t they worry that we would tell someone, that we would leak information? The only tie between us and the government was trust. They had to trust us because they didn’t have time to do otherwise. The war was going on and it wasn’t going to stop for us. Besides, who in their right mind would want to give out information that could hurt the United States?”

Questions for Reading 2
1. The first paragraph of the excerpt describes Ada’s reaction at hearing about the ‘Purple’ codes on the radio. Why would the declassification of the ‘Purple codes,’ years later, be shocking to hear about?

2. Consider Ada’s descriptions of her training and work at Arlington. How did these elements contribute to the overall success at Arlington in supporting the Allied Forces?

3. What may have living in the Washington D.C. and Arlington area have been like at the time? What details in the text make you think so?

4. “They had to trust us because they didn’t have time to do otherwise.”
What is the historical and societal significance of the U.S. Military placing such trust in women as cryptologists during WWII?

Reading 3
Ann Z. Caracristi

Black and white image of girls working on desks. Ann is pictured at the far-right desk, in Arlington Hall
Ann is pictured at the far-right desk, in Arlington Hall.


Portrait of Ann Caracristi during her older adult years.
Ann Caracristi


Bio: Ann Caracristi was born in 1921. She graduated from Russell Sage college in New York, was recruited by the Army SIS, and was sent D.C. to work in Arlington Hall. During the War, Ann’s work helped to reconstruct enemy code books, and she and her colleagues were some of the first to discover Japan’s planned surrender. Caracristi would later become the first woman to reach the highest supergrade in the National Security Agency (NSA) as Chief of Research and Operations in 1975 and would become the first woman to serve as NSA Deputy Director in 1980. After her years of dedication to cryptography and security services to the nation and received the highest civilian honor of Dept. of Defense Distinguished Civilian Service Award. She served on the Foreign Intelligence Advisory Board for President Clinton, post-retirement. She passed in January 2016.

Interview of Ann Z. Caracristi, Veterans History Project

Leslie Sewell, Interviewer: . . . Security clearances...what kinds of clearances did you all need?

Ann Caracristi, Interviewee: Oh, well that was sort of hilarious because they did--you know, you had to give references, and then they actually sent out investigators. And you would discover that all your parents' friends were being questioned about your reliability, etcetera, and this gave an aura of mystery to the whole endeavor. But they indeed did do on-site investigations, and we had to fill out a great deal of forms and things of that nature. And in fact, part of the reason I'm sure that we were held in our training school for the first several weeks that we were signed up was to be sure that that paperwork had been completed.

LS: If you had to say what the high point was of your work during the war, what would it be?

AC: Well, I guess it would be VJ Day [Victory over Japan Day, August 14, 1945]. [I] Went in at about two o'clock in the afternoon. We knew that the messages had been read, that the war was going to be over. And this was--the Japanese linguists who were in a wing of this large building, way down there [gestures], couldn't contain themselves. And the word went--swept like a fire through there. And we were told that we were not to tell any of our friends and relatives until, you know, four o'clock or something [laughs]. And then at four o'clock we all just left the building and congregated in Washington to celebrate the great day.

LS: And, before VJ Day, were there other accomplishments of the--of where you were working that really grabbed you? Anything--you mentioned something about the finding out about the code for the merchant marine ships, but were there any other things like that that struck you as really important?

AC: Well, you know, our efforts were divided, and there was a lot of "need to know" approach to the way we did business. And so those of us who were doing little portions of the effort were not usually aware of the full impact of the product that we were producing, at least in the part we were wor--I was working in. This was a big assembly line effort, truly. You know, several wings full of people, wings being large, long rooms, which you've seen pictures of, with tables. I mean, there were very little desks, there were very little front office, private offices. There were a few, but most of the work was being done in an almost assembly line sort of way. And the feedback was minimal in terms of specific accomplishments. Now there were times, you know, when something was--when a totally new system was broken into the--that information would be shared and there'd be great pleasure...

LS: Anything that I haven't asked you that you'd like to talk about?

AC: That you should've? [laughs]

LS: That's right, that I should've or that I didn't or that, you know, you think is important...

AC: No, I think the important thing was that the women who gathered together in our world worked very hard. And all of them had--none of us had an attitude of having to succeed or outdo one another, except in trivial ways; I mean, you wanted to be the first to solve a particular problem, or you wanted to be the first to get this recovery. But there was very little competition for, you know, for money, or anything of that nature, because everybody really assumed that when the war was over we would be leaving. I shouldn't say everybody; there were some people who had been there before and had careers, but the majority of the people considered it a temporary way of life.

LS: A temporary way of life...With a purpose, though?

AC: [laughs] Well yes, with a purpose, of course.

Questions for Reading 3:
1. How did Caracristi describe the security clearance process? Does this surprise you? Why or why not?
2. Consider the worksite images and Caracristi’s description of the workplace environment at Arlington. What do you imagine it would be like to be working in Arlington Hall?
3. Why did Caracristi say people considered the way of life as “temporary?”
4. Did this type of work end up being a “temporary” way of life for Caracristi? What evidence from her bio leads you to you think that?

Optional Activity 1: “The Invisible Cryptologists”

African Americans comprised approximately 15% of the workforce at Arlington Hall, which was unusually high for the period. (It is suggested Eleanor Roosevelt may have played a part in pushing for equity.) Many of the women who worked in the African American unit(s) remain unknown, and it is not widely known or documented that a special unit of African American women serving as ‘Code Girls’ even existed.
The NSA published “The Invisible Cryptologists: African-Americans, WWII to 1956.”
Support small student groups in doing a “jigsaw” activity, where each student group is responsible for learning and sharing information from one of the brief chapters. Focus on the beginning four chapters covering the WWII period:
Chapter 1 – Race Relations on the Home Front at the Onset of WWII
Chapter 2 – 1939-1946: African Americans Join the SIS
Chapter 3 – 1944-1946: The Commercial Code Unit 10
Chapter 4 – 1947: Changing Demographics
Support students in sharing important details of their chapters, and particularly connections to the themes of challenges that faced African American Cryptologists and their successful contributions, despite the unjust discrimination they faced. Support students in considering the especially difficult circumstances of African American women cryptologists.

Optional Activity 2: Creativity with codes

By late 2022 the United States Postal Service will have released a special edition stamp, “Women Cryptologists of World War II.”

Purple stamp with white outline. There are words scattered across the stamp. Some read "women cryptologists of world world II. USA." Another word is forever but it is crossed out.
Stamp designed by art director and designer Antonio Alcalá.


The stamp is designed with characters from the “Purple” code overlaid on an image from a World War II WAVES recruitment poster with an overlay of characters from the “Purple” code. Letters in the pane selvage (margins surrounding the set of stamps) can be deciphered to reveal key words, while the reverse side of the pane shares the cipher needed to decode. Have students design their own postage stamp honoring the work of women cryptologists in WWII. (You may wish to share other historical postage stamp images commemorating other important persons, places, or events, to explain the historical significance of a stamp design.)Students may design one based on . . .

  1. experiences shared in the readings from the lesson

  2. researching other women cryptologists of WWII

  3. and/or by using cryptograms and other primary source material from the NSA (for example, like in the design above, or can be printed for collage)

Additional resources to inspire:

Optional Activity 3: Cryptology Cartoons

Cartoons were widely shared during the WWII era and had various purposes: to entertain both those on the home front and overseaes, to share propaganda and encourage patriotism, but also to share information. They could be light-hearted or serious, or a mix in between.“Crypto Chris” was a weekly cartoon specifically focused on sharing information, and particularly, to encourage careful handling of secure information and classified documents. It was distributed to Army installations across the country and overseas. Crypto Chris would often depict humorous ways to NOT handle classified material. In the following picture, Crypto Chris posters are seen hanging above women working in a Communications and Security office in Arlington Hall. [For more information on “Crypto Chris” and its creation, read pp. 39 – 43, “Crypto Chris and World War 2” in Jud Hurd’s book, Cartoon Success Secrets: A Tribute to 30 Years of Cartoonist Profiles. [Free digital access here.]

Black and white photo of two women sitting and one standing at desks facing the wall. There are posters hung along the wall they are facing.
Communications and Security; Crypto Chris posters


Example of a “Crypto Chris” cartoon. Cartoon is of a serviceman discarding of important documents in a trash. Trash and documents are on fire.
Example of a “Crypto Chris” cartoon.

Jud Hurd, Cartoon Success Secrets: A Tribute to 30 Years of Cartoonist Profiles

Women Cryptologists at Arlington would have been familiar with “Crypto Chris,” but there wasn’t a female equivalent. What could WWII cartoons have looked like if women were depicted in their top-secret roles?Have students design their own cartoon (single frame, or multiple) depicting a humorous or serious aspect(s) of being a ‘Code Girl,’ using the narrative details described in Readings 1 – 3. Have students pretend that ‘Code Girls’ are the audience: with a goal to inform, bring humor, or help them feel “heard” in their work.Additional Support / extensions:


Ann Caracristi Collection(AFC/2001/001/30844), Veterans History Project, American Folklife Center, Library of Congress.

“Arlington Hall 1943” U.S. Army Intelligence and Security Command, U.S. Army archives.

Arlington County Virginia Government. (2019). GLUP Map.

Gentzke, Ann W. An American Hero. University of Buffalo.

Hannah, Theodore M. Frank B. Rowlett: A personal profile. 1980. NSA.

Historic American Buildings Survey, C. (1933) Arlington Hall Station, Arlington Boulevard, Arlington, Arlington County, VA. Arlington Virginia Arlington County, 1933. Vandyke, T., trans Documentation Compiled After. [Photograph] Retrieved from the Library of Congress,

Mundy, Liza (2017). Code Girls: The Untold Story of the American Women Code Breakers of World War II. New York, Boston: Hachette Books.

National Cryptologic Museum: “Ann Z. Caracristi Documents”

NSA. Genevieve Grotjan Feinstein. NSA Historical Figures.

O’Connell, K. 2021. “The Black Women Code Breakers of Arlington Hall Station.” Arlington Magazine.,women%20code%20breakers%20in%20total.

Weston, M. Celebrating Women in STEM: Ann Caracristi. 2018.UMKC Roo News.

Wilcox, J. Sharing the Burden: Women in Cryptology during WW 2. NSA.

Last updated: September 21, 2023