There’s nothing in Lee’s charcater to suggest he would knowingly send out one of his own divisions to be slaughtered. The only general to oppose the attack was Longstreeet, who had been behind the stone wall at Frederiskberg and knew how cut up attackers could get, trying to take a fortified position. Pickett was thrilled to finally get his divsion in the fight.
And Lee had done quite well on the first two days. The first day, the Union was driven out of the town and to the hills. The 2nd day, Sickle’s division was sluaghtered because he was an idiot and marched out 1/4 mile ahead of the battle line (lost a leg for it) . Lee came within an ace of rolling up the Union line at Little Round Top. If it had been anyone other than Chamberlain (who was one of the best soldiers in the entire war), Lee would have taken the hills and been able to flank Meade’s lines.
So the notion that Lee had failed miserable on both days is false. The first day went very well and he came so close on the 2nd day. The casualty figures bear this out: 23,000 union casualties after the fight, and 20,000-25,000 confederate. And that figure is AFTER Pickett’s charge. Before the assault, Lee had been doing very well.
Lee’s own explanation says it all: “I asked more of men than should have been asked of them.” He had come to believe his army could do the impossible (which it had throughout the war). Against Burnside, Hooker or McClellan the charge might have worked. But Meade was a capable general, and Hancock (whose division Pickett ran into) was an excellent soldier.
And as someone else pointed out: the war dragged on another two years. Had Lee seceretely wanted to surrender, he had ample oppurtunity after Gettysberg.
Just as a historical fact, the confederates best chance for victory came AFTER Gettysberg, when McClellan (anti-war), was set to trounce Lincoln in the election. Joe Johnston, the confederate commander at Atlanta, wouldn’t give Sherman a fight becasue he knew Lincoln would lose the election. Davis replaced Johnson with Hood, who promptly wrecked his army attacking Sherman, Sherman captured Atlanta, and Lincoln won reelection.