Magee, who was promoted to Major on May 15, 1917 and traveled to Base Hospital No. 12 in France. In August 1918, he was assigned as assistant to the chief surgeon Colonel Alexander Stark. While working with Stark, he participated in the St. Mihiel and Meuse-Argonne offensives from September - November 1918. He was awarded the Purple Heart for meritorious services in these operations.