[1] As head of the First Army, Miller was responsible for the training, readiness and mobilization of National Guard and Army Reserve units in all states and territories as they prepare for deployment as needed by United States combat commanders globally.

[2][3] He is the son of the late Colonel William H. Miller, who served in World War II, Korea, and Vietnam.

Additionally he served overseas in Iraq, Kuwait, Haiti, Hawaii, Korea, and Japan.

[1][4] Miller is also a graduate of the United States Army War College and holds a Master of Science in Management.

[1] Miller is also a member of the University of Southern Mississippi ROTC Hall of Fame.