Ezra Warner's book, Generals in Gray, claims that "McGowan's career and reputation were not excelled by any other brigade commander in the Army of Northern Virginia.

"[1] Following reconstruction, he was elected to the United States Congress but refused to take his seat, later serving as an Associate Justice of the South Carolina Supreme Court.

[2] Born to Irish parents in the Laurens District of South Carolina, McGowan's father was a prosperous farmer who had intended his son to study law.

Prior to the Civil War, McGowan practiced law as partner of Thomas C. Perrin and served in state politics.

[5][2] In late 1860 he was appointed to command a brigade of the South Carolinian militia, being a major general in the same, and was present at the attack on Fort Sumter.

After Gregg was killed in the Battle of Fredericksburg, McGowan was promoted to brigadier general (to rank from January 17, 1863) and took command of the Light Division's South Carolina brigade.