The "needs of the service" ultimately resulted in her being trained as a cryptanalyst. Following training at a secret base in Vint Hill, Virginia, she was posted first to New Guinea and later to the Philippines. Here she made her greatest military coup, discovering that the Filipina laundress for the WAC contingent was using pages from a Japanese code book to wrap the women's laundry.

In an interview, Douglas MacArthur said that WACs were his best soldiers; they worked harder, complained less, and were better disciplined. From reading Irene Brion's account of her World War II adventures, you learn that Irene and her distaff comrades in arms not only were everything MacArthur said, they also knew how to have a good time.