- After completing her nurse's training and working as a private nurse, Gladys Matheson enlisted for military service on May, 25, 1917, and departed with the 25th Draft on December 12, 1917, as a Lieutenant Nursing Sister.
- Gladys arrived for duty on January 8, 1918, in Eastbourne, England, at the No. 14 Canadian General Hospital Operating Room.
- On May 6, 1918, Gladys was ordered to serve at the No. 3 Canadian General Hospital in Boulogne, France. She was no longer in a hospital; the units were huts that were close to the front lines.
- Although the war ended on November 11, 1918, Gladys served in France until May 24, 1919, nursing patients through the Spanish Flu epidemic after the War.
- Upon her return to Canada, she served another year in Winnipeg at the Tuxedo Military Hospital.
- Gladys was demobilized in July 1920