Maybe it's the stifling humidity which makes the air so thick you have to shoulder your way through it like you're wading into surf. Or maybe it's the knowledge that you're walking over ground where kids half your age and younger bled their lives out into the grass and the earthworks.
Whatever the reason, you barely talk as you drive from point to point on the battlefield tour, getting out at stop after stop like you're walking some uniquely American version of the Stations of the Cross, until you come to the final site of the battlefield, though not the final site of battle.
The Battle of the Crater took place on July 30, 1864, when 4 tons of explosives went off in a tunnel that Union soldiers (mostly ex-miners from Pennsylvania) had dug under the Confederate lines. If you've seen the movie version of Cold Mountain? That's the big battle scene Jude Law walks away from. It was a total cock-up from start to finish. Because the black troops who were originally supposed to spearhead the Union charge might have suffered drastic losses, which would have made a bad headline, another regiment was sent in, and instead of advancing around the Crater, they walked straight into it. The resulting turkey shoot gave the Confederates enough time to rally for a counterattack.