One of the biggest names in cuisine is Julia Child (1912-2004). The celebrated chef gained worldwide fame as a television personality and author. She is credited for popularizing French cuisine in the United States with her first cookbook, Mastering the Art of French Cooking, and her television programs, such as The French Chef.

Millions were inspired to try her recipes, but there was one that she refused to share. In fact, she wouldn’t even talk about it. Unlike her many other savory dishes, this recipe was utterly repelling. It isn’t that it was a failure; it was a recipe she intentionally created during World War II when she worked as an intelligence specialist in the most-highly-classified spy agency in the United States.

Julia McWilliams was born in 1912 in Pasadena, California. A 1935 graduate of Smith College with a B.A. in History, Julia’s original ambition was to be a novelist. Those plans changed with the outbreak of World War II. She volunteered to serve her country through the Women’s Army Corps (WACs) or the U.S. Navy’s WAVES. That’s when the 6’2” (1.9 meters) woman discovered she was too tall to be accepted into the military.

Instead, Julia accepted employment at the Office of Strategic Services (OSS), the forerunner to the Central Intelligence Agency. She worked for the newly-appointed director, William J. Donovan.

When applying to work for the shadowy intelligence agency, Julia hoped to become a spy. Instead, she found herself engaged in much more mundane responsibilities. She worked as a file secretary and research assistant. By her estimation, she “typed over 10,000 little white cards” before earning a transfer. She earned $1,440 per year for her services. Her personnel file (accessible here) reveals some clues about her impatience in this role. Page 78 of the file quotes Julia: “Am supposed to get a promotion to typing bigger cards, but nothing has happened.”

Julia rose steadily through the ranks, moving from office to office as her intelligence and work ethic caught the attention and approval of her supervisors. She became the executive assistant to zoologist Harold Jefferson Coolidge, Jr., and Henry Field (curator of Chicago’s Field Museum of Natural History), assigned to a research project called “Emergency Sea Rescue Equipment Section.” It was while working on this project that Julia’s skills at recipe creation began to materialize.

The purpose of the Emergency Sea Rescue Equipment Section was to find a way to repel sharks. Shark attacks were quite rare — fewer than 20 in the less than three years since the start of the war — but the fear of attack was affecting the morale of soldiers. Additionally, there had been situations where naval explosives had been prematurely detonated by an inquisitive shark.

At last, freed from the mundane typing and filing assignments, Julia was free to unleash her creative energy. She recalled, “I must say we had lots of fun. We designed rescue kits and other agent paraphernalia.” Among the things developed under this program was “Shark Sense,” a training pamphlet with cartoonish illustrations, designed to educate soldiers and sailors about shark safety. (See the complete pamphlet here).

For a solid year, Julia and her team worked on their project, testing over 100 substances. Everything from sophisticated chemical compounds of alkalis and acids to things as simple as petrifying shark flesh fell under their inquisitive eyes.

The result of their efforts was a mixture of black dye and copper acetate. It smelled very much like a dead shark but would not wash away quite as quickly; one dose was good for 6-7 hours. With a success rate of slightly more than 60%, it was the best approach to date in keeping portions of the oceans shark free.

With the shark repellant project behind her, Julia feared she would be sent back to a desk job. Much to her delight, she became a field agent. She traveled to Ceylon (present-day Sri Lanka) and later to China.

With the conclusion of World War II, Julia’s position with the OSS was terminated on January 6, 1946. She returned to civilian life, but the trajectory of her life was different. While in Ceylon, she met a fellow-OSS employee by the name of Paul Cushing Child. Paul was an artist and poet, and he loved fine food. He introduced Julia to French cuisine, and she fell in love with the man and the food. On September 1, 1946, Paul and Julia were married.

They lived in Paris while Paul worked for the United States Information Agency. During this time, Julia knew she no longer wanted to be a novelist. Her newfound passion was cooking. Unlike the recipe she made while working for the OSS, she threw herself into concocting mouthwatering creations for her fellow humans. In 1951, she graduated from the world-famous Parisian cooking school, Cordon Bleu.

Although her plans for writing novels had changed, she was still determined to become a published author. In 1961, she released her first cookbook, Mastering the Art of French Cooking. It was an immediate sensation.

That same year, Julia appeared on Boston public television station WGBH to promote her book. She made her appearance as a guest on I’ve Been Reading, a show dedicated to book reviews. She arrived at the station with a hot plate, giant whisk, and eggs. She made an omelet, and almost everyone connected with that first appearance thought that would be the end of it. The television station began to receive requests from viewers, wanting to see more. Julia was asked to film three pilot cooking shows. Out of that came The French Chef. It went on the air on February 11, 1963, and ran for ten years. It was one of the first televised cooking shows in the United States, and it turned Julia into public television’s first celebrity. The unlikely star’s wavering voice, fondness for wine and butter, eagerness to hack away with a knife, and customary closing phrase, “Bon appétit,” made her name forevermore synonymous with cooking.

Julia died in 2004, at the age of 91, remaining one of the most recognizable names, faces, and voices in the culinary world. It was four years after her death that the National Archives declassified her personnel file and released it to the public. The recipe for the shark repellent was released by the CIA in 2015.