There are some spots at Gettysburg which have given me a really eerie feeling ever since I was a child. One is Spangler's Spring. I just can't describe the feeling I get there. Another is the Pennsylvania Monument. Another is the Permanent Flame Monument. I always felt scared there, but fascinated too.
As a child I loved Deveil's Den, but haven't ever felt the eerie feeling the other places I have mentioned give me. Spangler's Spring leaves the strongest sensation of all. I can feel heat, death, pain and blood--tons of blood there.
Try riding the Jackson Flank march path at Chancellorsville. A friend of mine and I did that a few years past in June, so the weather was very similar to the actual time. Granted, we were on bicycles, not horses, but as we were leaning up against a pair of trees having lunch he mentioned that he had no difficulty imagining us back then as a pair of cavalry pickets scouting the path.
I got a odd feeling when I dismounted at a stream crossing to rinse off my water bottle (dropped it and got it nice & dusty earlier). Just across from me was a sign stating that many of the soldiers on the march stopped there to fill their canteens. The road goes through the creek at that point.
I had a whole slew of "neck hair moments" one evening in June 1988 at (where else?) Gettysburg. This all happened the day after the 125th anniversary reenactment ended...
Right about dusk that Monday, my reenactment company of the 14th Tenn. traipsed down the hill to Willoughby Run (where the original 14th Tenn was on July 1, 1863), where we performed an impromptu ceremony of dipping the corner of our battleflag into the Run...when that was finished, as we stood around talking (very quietly), several interesting things happened:
1) As we were discussing the souls of all the boys who had died there, suddenly hundreds of fireflies lit up simultaneously!
2) While we stood there in amazement, quietly now, I could hear faintly upstream a male voice shouting what were obviously commands...and no-one lives anywhere near that area (in those woods).
3) Then, I could feel a (friendly) hand rest upon my shoulder. Needless to say, no one was there.
4) A little later (in the moonlight IIRC) after we had arrived near the "copse of trees" along with a bazillion other reenactors (the park rangers wisely ignored everyone that evening) and stood there near the angle talking quietly and reverently to some others, I felt that hand on my shoulder again...
I've had quite a few of these moments. At Wilderness, I was in deep in the woods and in some deep thought, having a nice quiet walk on the Gordon Flank Trail, when I came up on a small clearing. All of a sudden, about a zillion blackbirds took off yackin' & cacklin' like crazy. I thought I was being attacked as they were very LOUD. To top that off, a few seconds later, a reenactor came up from behind (there was a big three-day event in the area) and that scared out what little crap had remained from the first assault. All ended with a good hearty laugh.