He graduated from the United States Military Academy in 1884 and was commissioned second lieutenant in the Second Artillery. He early made himself an authority on ordnance. Then-Captain Lewis of the Sixth Artillery was sent by Adjutant General Henry Clarke Corbin to Europe in 1900 to study that subject, his report resulting in the re-armament of the field artillery. By successive promotions, he rose to the rank of colonel in 1913, and was retired in that year for disability incurred in line of duty. He was awarded the Franklin Institute's Elliott Cresson Medal in 1919.