 In 1940, she was appointed a member of the American Mathematical Society's Cryptanalysis Committee, for which she worked until the end of World War II.She maintained her teaching job for most of this period, though, (except for taking leave in 1944-45) and went to great lengths to keep her Cryptanalysis Committee work secret.Her health, however, continued to deteriorate, and in 1946 the University of Illinois placed her on permanent disability leave.