James Longstreet (1821–1904) was a Confederate general during the Civil War. He was a capable battlefield commander. He was not, however, as aggressive or as popular as Thomas Jonathan "Stonewall" Jackson (1824–1863). The inimitable Jackson served as General Robert E. Lee's second in command until his death at Chancellorsville in May 1863. Longstreet assumed Jackson's role for the decisive three-day battle at Gettysburg. The Confederacy's loss there doomed it to eventual defeat. Longstreet's performance at Gettysburg, especially on the third day, has been the subject of much debate among historians. Many students of the battle have speculated that the South could have won if Longstreet had performed as well as Jackson might have. But Jackson's performance is just speculation, since he was dead by then.
First, Longstreet had to obey Lee's orders at Gettysburg. Good soldiers must obey or the chain-of-command breaks down. He had no choice but to follow Lee's directives. In addition, Lee had not yet lost a major battle. Second-guessing him was problematic and difficult. Longstreet certainly could not have assumed command of the army. Lee was too well respected; furthermore, Longstreet would have been guilty of insubordination. Taking over the Confederate army was not an option that Longstreet would have considered.
Second, Longstreet urged Lee not to attack on the third day. Lee overruled this advice. There was not enough time or an opportunity for Longstreet to convince other Confederate generals to support his cautious strategy for the third day at Gettysburg.
After the South lost the war, Lee was adored and Longstreet was vilified. Longstreet became a Republican after the war, so Southerners viewed him as a traitor. But the blame for the South's loss at Gettysburg must be attributed to Lee. Lee was overconfident. His army was handicapped by poor reconnaissance. After Gettysburg, Lee accepted blame for the defeat and offered to resign his command. President Jefferson Davis refused, and Lee commanded the Southern army until their final surrender in 1865.