[1] When Lee launched the Gettysburg Campaign in June 1863, the Third Corps was initially left along the former Confederate positions along the Rappahannock as a rear guard, following the rest of the army on the 15th after Lee was convinced that Union commander Joseph Hooker would not launch an attack on Richmond.

[2] On the morning of July 1st, Heth encountered the leading elements of the Army of the Potomac, thus starting the three-day Battle of Gettysburg.

Ambrose R. Wright was able to briefly pierce the Union center on Cemetery Ridge but was forced to retreat.

Before he was able to launch an attack with his division, Pender was mortally wounded by an artillery shell and was replaced by Brigadier General James H. Lane.

[5] Pettigrew's and Trimble's divisions reached the stone wall on Cemetery Ridge but failed to breach the Union line; the 55th North Carolina Infantry was credited with making the farthest advance of any Confederate regiment during the attack.

Artillery fire and a counterattack by the Vermont Brigade forced them to retreat, with several dozen Confederates falling prisoner and two battle flags captured.

Heth's division served as the rear guard as the army marched over the Potomac on July 14; during the Battle of Falling Waters, Pettigrew was mortally wounded during a Union cavalry charge.

On the second day, the Union army attacked at dawn and quickly drove Hill's troops back in confusion.

[10] During the march to Spotsylvania Court House on May 8, Hill fell ill and was replaced by Jubal Early from the Second Corps.

[13] Following Cold Harbor, the corps was rushed to the Richmond-Petersburg area where it was engaged in the three-day Second Battle of Petersburg.

Hill was ill several times during the siege, which forced him to turn operational control of the corps over to his division commanders, such as at Ream's Station.