John Bowyer Brockenbrough was born in Lexington, Virginia on March 6, 1836. He had attended Washington College and graduated from the University of Virginia and the Washington College Law School. He then practiced law in Lexington. He was an organizer of the Confederate States of America's Rockbridge Artillery at the beginning of the American Civil War. While serving with that battery in August 1861, he was wounded and resigned. In 1862 he was elected Captain of the 2nd Maryland (CSA) Artillery. He was wounded at Fredericksburg in December 1862. He was promoted to Major in 1863 and retired in 1864.
After the war, he practiced law in Lynchburg, Virginia, until 1886, when he was appointed special agent for the Department of the Interior by President Cleveland. He moved to Baltimore in 1900. He died on November 17, 1901.