As a young boy I walked the field at Gettysburg. They had old guys dressed in Union or Souther uniforms, who were near to the conflict talke about it to visitors.
It is hard to imagine 10,000 men march into a wall of steel death only to breach the split rail fencing and a few surrender.
Its hard to believe that after Antietam and especially Frericksburg, Lee believed that a mass Napoleon-style assault would work. That’s some stubborn thinking from an otherwise brilliant and innovative commander. After the first day, Longstreet wanted to side-step the Union army and get between it and Washington, forcing the Union troops be the ones to attack. Would probably have worked better. That was the basis of the post-war feud between them.