Clark received the country's highest award for bravery during combat, the Medal of Honor, for his action at Brooks Ford, Virginia on May 4, 1863.

He enlisted with the 6th Maine Infantry in July 1861, and was commissioned as a lieutenant in February 1862.

He was active in the Grand Army of the Republic, and was elected its national judge advocate general in 1905 and the department commander of Iowa in 1906.

[4][5] He was also a companion of the Iowa Commandery of the Military Order of the Loyal Legion of the United States.

[6] Clark died at his home in Cedar Rapids on December 22, 1913, and his remains are interred at the Oak Hill Cemetery.