In January 1918, he sailed for France, and as a platoon leader in the 6th Marine Regiment, participated in the Aisne-Marne Defensive (Battle of Chateau-Thierry), where he was wounded in action; also fighting at Belleau Wood; Bouresches; and Soissons. In the St. Mihiel Offensive, he was so seriously wounded that he was evacuated to the United States in October 1918, spending a year in the hospital and undergoing nine surgeries.