I just found this forum, and I know I'm coming in very late. I first heard of this little action when I was driving back to CA from Gettysburg in July, 2008. I had had to pull off and check the width of the trailer I had a cannon on - there was road construction and the lanes narrowed to 10 feet, and I wasn't sure how wide it was. Pulled into a gas station and some older gentlemen came up to talk to me and told me of the cemetery and the graves of Thornton's men. Then one guided me to it. This got me curious about it.
Here is one NY Times piece about it: http://query.nytimes.com/gst/abstract.html?res=9B01E2D8143EEE34BC4951DFB166838F679FDE
The little bits of history you come across by happenstance.