Photo By Lori Stewart | Ann Caracristi, far right, at work at Arlington Hall during the war (NSA Photo)... read more read more
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by Lori S. Stewart, USAICoE Command Historian
ANN CARACRISTI JOINS THE SIGNAL INTELLIGENCE SERVICE
On Jun. 8, 1942, Ann Z. Caracristi graduated from Russell Sage College in Troy, New York, and set off for her new job with the War Department’s Signals Intelligence Service (SIS). She did not anticipate, at that time, it would become the first step on her path to being deputy director of the National Security Agency (NSA) thirty-eight years later.
The Army had established the SIS in 1930 as its consolidated code making and breaking organization. Under the leadership of William Friedman, the SIS was headquartered at Arlington Hall, Virginia, where 5,700 civilians, 650 officers, and 1,600 enlisted men and women toiled around the clock cracking the codes of the enemy. One of those many civilians was New Yorker Ann Caracristi.
In 1942, as 21-year-old Ann prepared to graduate from Russell Sage College with degrees in English and history, she anticipated working as a journalist in the city. Unbeknownst to Ann, she had been recommended for employment at SIS by the college’s dean. Wanting to do “something useful,” Ann accepted SIS’s offer. When she graduated on Jun. 8 and boarded a train for Washington, D.C., she knew only that the work was “secret.”
Upon arriving in D.C., Ann was enrolled in a cryptanalysis course at George Washington University. Within a month, however, having completed less than half the course, she was pulled from class and put to work at Arlington Hall. Despite knowing nothing about the Japanese language, Ann was assigned to the Japanese Army Codes Section. As part of the section’s Traffic Handling Team, she reviewed and sorted thousands of coded enemy messages that had been intercepted by monitoring stations around the world. The messages were prepared for punch cards, which were fed into IBM tabulating machines that searched for patterns in the streams of numbers that made up the enemy’s code. The patterns would hopefully provide clues as to how to break the code.
As Ann gained experience, she became head of the research office in the Address Systems Section, where personnel studied the parts of radio messages indicating where they originated and where they were sent. The section was able to identify four major Japanese military radio networks, which helped the Allies determine the disposition of Japanese forces throughout the Pacific.
Significantly more difficult to break, however, were the encryptions shielding the designations of the specific units and the actual content of the messages. One of the office’s most momentous successes was its contributions to the breaking of the Japanese Water Transport Code, allowing analysts to regularly read messages about Japan’s transport and supply fleet. The decoded messages provided accurate information on order of battle, garrison strengths, reinforcements, and supply problems of the Japanese Army. This intelligence enabled Allied aircraft and submarines to interdict enemy shipping, effectively severing the Japanese island garrisons from their supply lines. The breakthrough also opened the way to reading the Japanese Army’s other high-level code systems, making it a critical contributor to Japan’s eventual defeat.
In later years, Ann reflected on her contributions to the war effort: “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.” The importance of her contributions, however, was well known. After the war, Ann left the SIS for a more staid life as a journalist but, when the SIS (renamed the Army Security Agency) reached out in the early Cold War to see if she was interested in returning, she jumped at the opportunity. In 1952, she transferred to the NSA, eventually rising to the highest civilian grade and becoming the agency’s deputy director in 1980. She retired two years later, at which time President Ronald Reagan awarded her the National Security Medal. A decade later, President Bill Clinton appointed her to the Foreign Intelligence Advisory Board. Ann Caracristi’s long distinguished career in cryptology was recognized in 2012 when the NSA inducted her into their Hall of Honor. She passed away in January 2016.
For more information on Ann Caracristi, see David Sherman’s "Ann’s War: One Woman’s Journey to the Codebreaking Victory over Japan," published by the National Security Agency’s Center for Cryptologic History. Ann also conducted an oral history interview for the Veteran’s History Project, available on the Library of Congress website: https://www.loc.gov/item/afc2001001.30844/.
New issues of This Week in MI History are published each week. To report story errors, ask questions, request previous articles, or be added to our distribution list, please contact: TR-ICoE-Command-Historian@army.mil.
| Date Taken: | 06.06.2025 |
| Date Posted: | 06.06.2025 16:33 |
| Story ID: | 499903 |
| Location: | US |
| Web Views: | 26 |
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