Which Confederate army did Robert E. Lee command at the Battle of Gettysburg?

At the Battle of Gettysburg, Robert E. Lee commanded the Confederate Army of Northern Virginia. It was the principal Confederate army in the Eastern Theater and the force Lee led during his 1863 invasion of Pennsylvania.

Lee took command of the army in June 1862 after General Joseph E. Johnston was wounded at Seven Pines. The force had previously been known as the Army of the Potomac and the Army of Northern Virginia in its early reorganization; under Lee, the latter name became permanently associated with the army that defended Richmond and fought the Union Army of the Potomac.

Lee’s army crossed the Potomac River in June 1863 and concentrated around Gettysburg after Confederate and Union forces unexpectedly collided there. The three-day battle ended with Lee’s retreat to Virginia after the failure of the July 3 assault commonly called Pickett’s Charge.

The answer is sometimes confused with the Army of Tennessee, another major Confederate army that operated primarily in the Western Theater. The Army of Northern Virginia was Lee’s command at Gettysburg, while the Confederate army’s overall commander was not established until Lee briefly became general in chief in 1865.