Clarence Derrick was born in Washington, DC, in September 1837. He attended the U.S. Military Academy from 1857 to 1861, graduated in June 1861, and was promoted briefly into the U.S. Army. He resigned his Corps of Engineers commission and was dismissed in July 1861. He enlisted in the Confederate Army almost immediately. He worked as General John Floyd's adjutant with the 51st Regiment, Virginia Infantry. The regiment was later reorganized as the 23rd Battalion, Virginia Infantry. Derrick was a Lieutenant Colonel and in command of the battalion by April 1862. He was captured at Winchester, September 1864 and released from Fort Delaware June 1865.

Following the war, he was a lawyer (and possibly a professor of mathematics) in Marion, Alabama. He continued to practice law in Greensboro, Alabama, and eventually established a cotton plantation. By 1880, he was livingin Greensboro with his first wife's (Fannie Peay) family. After 1900, he appears to have retired to Pennsylvania. He died in 1907, while on a visit to Greensboro, survived by his third wife, Alice Paschall Darlington Derrick. He did not have any children.

Sources:

• Ancestry.com
• Scott, J. L. 1991. 23rd Battalion Virginia Infantry. Lynchburg, VA: H. E. Howard.