What battle did thomas Jackson get his nickname of stonewall?

On April 27, 1861, Virginia Governor John Letcher ordered Colonel Jackson to take command at Harpers Ferry, where he would assemble and command the famous "Stonewall Brigade", consisting of the 2nd, 4th, 5th, 27th, and 33rd Virginia Infantry regiments. He got his nickname "Stonewall" from the fact that he and his brigade never retreated but always stood as a stone wall.

Jackson earned the name of "Stonewall" at the Battle of First Manassas or First Bull Run.