In recognition of his service, in 1866, he was nominated and confirmed for appointment as a brevet brigadier general of volunteers to rank from March 13, 1865.

When he was nineteen, he entered the office of A. W. Gilbert, then the city surveyor of Cincinnati, and thoroughly mastered the duties of the position.

For gallantry at Shiloh, he became commandant of artillery in Thomas J. McKean's division and later chief of staff of the XVII Corps.

Hickenlooper served through the Atlanta campaign as an engineer with distinguished honor and participated in Sherman's March to the Sea, and the advance through the Carolinas.

He published two books, Competition in the Manufacture and Delivery of Gas (1881), and Incandescent Electric Lights for Street Illumination (1886).He became active in veterans affairs, particularly those of the Society of the Army of the Tennessee, serving as its Corresponding Secretary, where he worked tirelessly for the erection of monuments to the memory of his friend and mentor, General James B. McPherson In 1879, he was elected the 15th lieutenant governor of Ohio under Governor Charles Foster and declined a renomination in 1881.

[4] On January 3, 1912, a statue in honor of Hickenlooper was erected in Vicksburg National Military Park.