During my recent visit to the battlefield, I was at the Trostle farm to match up a modern photo with O'Sullivan's classic image of the Trostle barn with a number of dead artillery horses in the foreground. I reshoot the matching now version every visit always going for the elusive perfect match. Before this last trip, I beleived I had established the matching camera location. However, this time when I compared O'Sullivan's original photo to the actual location, I noticed a clue to the correct camera location that I had previously overlooked. What I had thought to be two dead horses are actually two rocks close together that form a gap that is easy to match up with today. When I matched the gap between the rocks with the original pic, I believe that correctly established O'Sullivan's camera position. In the original photo below, I have an arrow pointing at the gap, specifically at the rock I am sitting on while holding up the original O'Sullivan photograph. As you see, the tree now blocks the barn in the modern view. Note: My modern photo is only intended to point out the matching gap in the rocks, not to match the entire O'Sullivan frame.