Mabel Dymond Peel was one of 12 women from the Women's Army Auxiliary Corps (WAAC) who were recruited by General Headquarters (Intelligence) to assist the signals intercept code breaking effort. They were known as the 'Hush WAACs' due to the secretive nature of their work. Peel was working previously as a censor in German for the war office, and so was selected for her German language skills. She was the first woman to be admitted into the Intelligence Office at GHQ in 1917.

Peel was sent to France and was operating only 28 miles from the front, enduring frequent bombing raids. The work was hard. The WAAC allowed a fortnight's leave every twelve months. The men in the office doing the same work were allowed leave every 6 months.

When the war came to an end, Peel's service was finished. She later moved to Rouen and, concerned by the large number of ex-servicemen forgotten about after the war, she established a branch of the British Legion there.