The extended Bryan family later settled in Brazoria County, and his parents operated a sugar plantation called Peach Point.

Bryan served in the Mexican–American War as a private in the Brazoria company commanded by Captain Samuel Ballowe.

During the Civil War Bryan sided with the Confederacy, and served as volunteer aide-de-camp on the staff of Paul Octave Hébert, afterwards serving as assistant adjutant general of the Trans-Mississippi Department with the rank of major.

He established a cotton bureau in Houston, Texas in order to escape the Union blockade along the Gulf.

[1] His grandfather, Moses Austin, had initially obtained permission from Mexico to serve as an empresario to settle Texas.