The Confederate corps led by General Longstreet was the First Corps.

Longstreet's leadership played a crucial role in the Battle of Gettysburg, where he oversaw major segments of the combat, especially on the second and third days. His corps launched critical attacks on Union strongholds, most notably during the notorious Pickett's Charge. While Longstreet's experience and tactical skills were vital, he frequently clashed with General Robert E. Lee over strategies for an offense. His command significantly shaped the battle's dynamics and its final results.