Edith Campbell enlisted as a nursing sister in September 1914 and served with the Canadian Expeditionary Force until April 1919. On 31 May 1918 she was serving at No. 1 Canadian General Hospital, Etaples, France, when German bombs hit the building. Her own office was wrecked. She attended wounded nurses and inspired others under her charge.

Matron Campbell was awarded the Military Medal. She was also twice Mentioned in Despatches (June 1915 and December 1917).