William Clark, legislator and soldier, the son of Martha B. (Wall) and William Clark, Jr., was born in Milledgeville, Georgia, on November 8, 1828. The family moved to Texas in 1835 and settled in Sabine County, where the junior Clark grew into adulthood. He served four months in Company K, Second Texas Mounted Volunteers, during the Mexican War and participated in the battle of Monterrey. He was admitted to the bar in Shelby County in 1852 and practiced in San Augustine County. He settled permanently at Nacogdoches in September 1854. In the House of the Eighth Legislature (1859–61) Clark represented Nacogdoches County. When Governor Sam Houston called the legislature into special session, Clark voted against calling the Secession Convention. However, he was elected to that convention and there voted for separation from the Union. He raised an infantry company at Nacogdoches. On January 13, 1862, his unit entered the Confederate Army as Company G, Twelfth Texas Infantry. He was elected the company captain and was eventually promoted to lieutenant colonel of the regiment. After returning home he resumed his law practice and served as attorney for Nacogdoches County and for the Houston, East and West Texas Railway Company. On July 11, 1867, Clark married Amelia Taylor, daughter of Charles S. Taylor, in Nacogdoches; they had ten children. Clark died on January 6, 1884, and was buried in the Oak Grove Cemetery in Nacogdoches.