upon the graduation, he served with the marine barracks at port royal, south carolina, and later was attached to the marine detachment aboard the battleship uss "arizona". miller, who was meanwhile promoted to the rank of first lieutenant in september 1916, sailed with "arizona" to guantanamo bay, cuba, for expeditionary duty. he received the promotion to the rank of captain in october 1917 and was appointed commanding officer of headquarters company within 13th marine regiment under colonel smedley butler. his regiment sailed within 5th marine brigade under brigadier general eli k. cole to france in september 1918 and miller was appointed to the temporary rank of major at the same time. but it was too late to see combat, and he spent the next year of service in brest until august 1919, when he was ordered back to the united states.