Jackson, Thomas Jonathan (1824–1863), a United States and Confederate army officer. Early in the Civil War he received the nickname “Stonewall” when his men held firm in the First Battle of Bull Run. Jackson was one of the ablest officers in the Civil War. He was General Lee's right-hand man. grasping and executing Lee's plans with skill and speed.

Jackson was born in Clarksburg, Virginia (now West Virginia). He graduated from West Point in 1846. Jackson distinguished himself in the Mexican War (1846–48) and was brevetted a major. In 1851 he resigned to become a professor at Virginia Military Institute.

Jackson became a brigadier general in the Confederate army in June, 1861, and a major general in October. From March to June, 1862, he commanded a small army against three Union forces in the Shenandoah Valley. In this campaign, his men moved so fast that they became known as “foot cavalry.” Jackson's action deprived the main Union army of 40,000 reinforcements needed for a march on Richmond. Rejoining the main Confederate army, now under Lee's command, Jackson fought in the Seven Days' Battles, the Second Battle of Bull Run, and the battles of Antietam and Fredericksburg. In October he was made a lieutenant general and commander of one of the two corps of Lee's Army of Northern Virginia.

In Jackson's last battle, at Chancellorsville, May 2–4, 1863, he surprised and shattered the Union right wing with a flanking attack. As he was returning to the Confederate lines, his own men fired on him by mistake. He fell wounded and died a week later.

Jackson was elected to the Hall of Fame for Great Americans in 1955.