[2] Vroom was educated in Trenton and graduated from Rensselaer Polytechnic Institute in 1862 with a civil engineering (CE) degree.

[1] Contemporary news accounts described Vroom as noticeably handsome, with one stating that at six feet four inches and generously proportioned, he was one of the army's most distinguished looking men.

[3] In August 1862, Vroom joined the Union Army for the American Civil War and received his commission as a first lieutenant in the 1st New Jersey Infantry Regiment.

[4] At the end of the war, Vroom was serving as inspector of the XVI Corps Cavalry force commanded by Benjamin Grierson in Mississippi.

[4] He was promoted to first lieutenant in July 1866[1] and served throughout the western United States during the American Indian Wars.

[4] Vroom was promoted to colonel in January 1900,[1] and in July 1902 he was assigned as inspector general of the Philippine Division during the Philippine–American War.