Born in North Andover, Massachusetts to Canadian-born Catherine (née Stewart) and Scottish-born James B. Miller,[1][2] Miller attended the public schools. He graduated from Cannon's Commercial College, Lawrence, Massachusetts, in 1917. During the First World War enlisted August 5, 1917, as a private in the United States Army and served in the Air Service in the 80th Aero Squadron and 1104 Aero Squadrons. Later commissioned a second lieutenant. He was injured in an airplane crash in France in 1918, resulting in the loss of both legs. He was discharged April 26, 1919. Patient in United States veterans' hospitals 1919–1931. He moved to Wethersfield, Connecticut, in 1926. He engaged in the insurance business in 1931.