The National Archives in August of 2008 released unclassified personnel files, including those of Julia Child and 24,000 other spies. Julia had a disappointing employment record before working for wartime intelligence. Julia reportedly attempted to join the Navy right after Pearl Harbor attack, but was too tall and rejected. I don't think the armed services were accepting women at that time anyway. This is what brought her to the attention of the intelligence community at the Office of Strategic Services.
According to an ABC news story (click here), "Nevertheless, she became a top secret researcher for the director of the OSS, the legendary William "Wild Bill" Donovan. And, later, she worked to reduce the threat of U-boats, the deadly Nazi submarines."
She went on to become such a part of U.S. culture that she was satirized on Saturday Night Live, and a there was Google doodle to celebrate her 100th birthday.
Here is an interview with an author who wrote about Julia and her husband, Paul and their work as spies. If you are interested in learning more, this looks like an interesting book. I think I will be getting it myself.