In February 1916, Page enlisted in the Australian Army Medical Corps. He served as chief medical officer aboard the troopship "Ballarat", and was then stationed at an army hospital in Cairo for several months. He was transferred to a hospital in England in July 1916, and concluded his service as a surgical specialist at a casualty clearing station in France. Page returned to Australia in March 1917 and was discharged from the military in July 1917. Although his active involvement in medicine declined as his political career progressed, he was frequently called upon to treat his fellow MPs or parliamentary staff. This was particularly true after the federal government moved to Canberra, as the new capital had only a handful of qualified surgeons. In 1928, for instance, he performed an emergency appendectomy on Parker Moloney.