He later served as an adjutant of the 29th Iowa Volunteer Infantry Regiment, from October 19, 1862, to February 21, 1865, including service during 1864 as aide de camp and Inspector General on the staff of Brig.

[1] He was a major of the same regiment and aide de camp and acting assistant adjutant general on the staff of Maj. Gen. Frederick Steele from February 21, 1865, to August 10, 1865.

[1] After the war, he studied law, was admitted to the bar in 1866, and commenced practice in Council Bluffs, Iowa.

In 1884, he was elected as a Republican to the United States House of Representatives from Iowa's 9th congressional district, and served in the Forty-ninth U.S. Congress.

Lyman resumed the practice of law in Council Bluffs, where he died of paralysis, after a long period of sickness.