After graduating from the U.S. Military Academy at West Point, N.Y., in 1847, Hill saw routine service before the outbreak of war. He joined the Confederate Army as a colonel, serving primarily in northern Virginia. His regiment was held in reserve at the First Battle of Bull Run (July 1861), and, as brigadier general, he fought at Williamsburg (May 1862) in the Peninsular Campaign. As major general he led his “Light Division” in the Seven Days' Battles (June) at Mechanicsville, Gaines's Mill, and Frayser's Farm. Hill's troops helped repel the Federal attacks at the Second Battle of Bull Run (August) and assisted in capturing Harpers Ferry (September 14). Three days later he arrived at Antietam in time to check decisively the Federal assault against Gen. Robert E. Lee's right wing. Hill participated in the Battle of Fredericksburg (December) and was wounded at Chancellorsville (May 1863).

Promoted to lieutenant general in command of the III Corps, he had a prominent role in the Battle of Gettysburg (July). He was engaged in the Battle of the Wilderness (May 1864) and at Petersburg (April 1865), where he was killed.