Originally posted by monochrome Battle of Gettysburg as William Henry Jackson, but I would already have a box camera instead of only a sketchpad.
William Henry Jackson was at Gettysburg, but as a soldier. He served for 2 years and his brigade was at several major battles but never posted to the front lines. He never personally saw combat so to speak. He didn't take up photography until after the Civil War. Started out as a painter and worked coloring photographs at one time. Did a good chunk of the Oregon trail as a bullwhacker too.
But I agree with the choice. It would be awesome to be the first person to photograph Yellowstone. BTW, He lived to be 99 and used everything from the old wet process to early 35mm Leica cameras.
The book "William Henry Jackson: Framing the Frontier" is a good read on his life.