He graduated from the United States Military Academy at West Point in 1821, and briefly served as second lieutenant of artillery before resigning in February 1822.

He was elected to the South Carolina House of Representatives in 1828, serving in that body through 1831.

[1] Following South Carolina's secession, he was a Confederate presidential elector.

His family was able to maintain two houses in Georgetown and several plantations, including the Allston ancestral home on the Pee Dee River, Chicora Wood—one of the five plantations Robert Allston owned, with over 9,500 acres and at least 690 enslaved Blacks, making him the eighth largest enslaver in United States history.

[2] Born in 1801 as a younger son to a Georgetown rice plantation who died when Robert was a child.

She was the younger sister of James Louis Petigru, a well-known Charleston SC lawyer.