Best book before visiting Gettysburg?

I want to get some extra perspective before going this summer. I have Gettysburg and Battle Cry of Freedom. I take a while to finish a book so I'm worried Gettysburg may not get completed in time, especially if it drags on and I find it slow.

Doesn't seem like battle cry of freedom has a dedicated Gettysburg section?

I'm reading both regardless as I'd been to Gettysburg as a kid and was always interested in the war but I'm open to suggestions on a what to read before going.

I'll probably rewatch ken burns too.