Another twist of fate - another young man with the same name involved in the same war, both entering the military at the age of 18:

Henry Clay Carman

Henry was born on 9 June 1844 in Bath, Mason County, Illinois. At the age of 18 his slipped away from his then home in Fremont, Iowa to Missouri where he enlisted in Company D, Fifth Missouri Cavalry. 

Most of the activities of the Fifth Missouri were guerrilla warfare operations within Jackson County, Missouri, so he didn't see much of the country as did the other Henry Clay Carman.  But young Henry was twice wounded, having been shot in the knee and in the arm by a bushwhacker at one time. He was also hospitalized several times for illness and injuries. He was given an honorable discharge on June 22, 1863 at the end of his enlistment.

Henry returned home to Iowa after the war and wasting no time, married Emma Jones on 12 July 1863 and there they farmed for 14 years.  Henry and Emma then relocated to Cook, Johnson County, Nebraska where they lived out the rest of their lives.

It is said that Henry, in his declining years ate fried eggs and pancakes three times a day.  Henry died 28 October 1938 at the age of 93.

From Shirley Wilkerson Weihing, " I remember [great] Uncle Henry. He had beautiful white hair."

from "Portrait and Biographical Album of Johnson and Pawnee Counties, Nebraska" (1889) & "The Carman Family 1631-1981" by Carrol Carman Hall (1981).