What did Thomas "Stonewall" Jackson do to gain his nickname and become a noted Civil War figure?
During the first battle of Bull Run, Stonewall Jackson commanded a brigade of Virginian Confederate Troops that held back the Union attack. Jackson got the nickname "Stonewall" Jackson for this stand.
Jackson also became an able assistant to General Robert E. Lee until his death after the battle of Chancellorsville. The War might have been different if he had lived.