Jackson gained his famous nickname

at the

Battle of Gettysburg

First Battle of Bull Run

Second Battle of Bull Run

Battle of Chancellorsville

Jackson earned his nickname at the First Battle of Bull Run (also known as Manassas)

Explanation:

in July 1861 when he rushed his troops forward to close a gap in the line against a determined Union attack. Upon observing Jackson, one of his fellow generals reportedly said, "Look, men, there is Jackson standing like a stone wall!"-a comment that spawned Jackson's nickname.

First battle of bull run