When the First World War erupted, Dix volunteered for the German Army. He was assigned to a field artillery regiment in Dresden. In the autumn of 1915 he was assigned as a non-commissioned officer of a machine-gun unit on the Western front and took part in the Battle of the Somme. In November 1917, his unit was transferred to the Eastern front until the end of hostilities with Russia, and in February 1918 he was stationed in Flanders. Back on the western front, he fought in the German Spring Offensive. He earned the Iron Cross (second class) and reached the rank of "vizefeldwebel". In August of that year he was wounded in the neck, and shortly after he took pilot training lessons.