St Clair was born October 1, 1802 in Kentucky, the fifth of seven children born to John Dyer and Margaret (Hester) Patton. The Patton family emigrated to Texas in March 1832 and settled in what is now West Columbia in Brazoria County. On March 1, 1836, St Clair enlisted in the Texian militia to fight for independence from Mexico. As a member of Captain William H. Patton's Columbia Company, he fought at the Battle of San Jacinto and afterward discharged on June 1. St Clair died in Brazoria County on December 2, 1849 and buried in the Patton family cemetery, now located in the Varner-Hogg Plantation State Park in West Columbia.