Unable to properly support her family, she apprenticed young Robertson four years later to a hatter, who moved with the boy in 1824 to St. Louis.

He returned with his wife and several relatives to Texas in December 1837, buying land and settling in Washington-on-the Brazos.

Robertson was a delegate to the state Secession Convention in January 1861, and subsequently raised a company of volunteers for the Confederate army and was elected as its captain when it became a formal part of the newly raised 5th Texas Infantry Regiment in the brigade of John Bell Hood.

Robertson became popular with his soldiers due to his unusual concern for their welfare, giving rise to his nickname, "Aunt Polly."

Those attacks culminated with the fight for Devil's Den, during which his 1st, 4th, and 5th Texas regiments, as well as his 3rd Arkansas Infantry, took heavy casualties that ultimately resulted in their taking their objective, despite being greatly outnumbered by Union forces.

However, Robertson's performance in the subsequent East Tennessee campaign invoked the wrath of both Longstreet and division commander Micah Jenkins.

Longstreet filed formal court-martial charges against General Robertson, alleging dereliction of duty and accusing him of pessimistic remarks.

Following the collapse of the Confederacy and the surrender of the remaining Texas forces, Robertson returned to his home in Independence and resumed his medical practice, a period marked by mourning when his wife died in 1868.

Two years later, he served as passenger and emigration agent for the Houston and Texas Central Railroad.