During the Civil War small rock piles have sometimes been found to be defensive positions in either guarding a strategic road or an important area. If the ground directly behind the rock piles is indented (a depression) on all the same side, then that is a telling sign. If the area around the rocks is evenly flat ground then probably not. Many of these defensive positions never actualy saw battle.
You mentioned you are on the route near the Civil War campaign of Corydon. Maybe the rock piles were guarding something strategic....do they face an old road coming in front of them? Maybe they were guarding a cave of gold that is nearby
Here are all the battles fought in Indiana. Only 4 are documented.
- Newburgh Raid, Location: Newburgh, July 16, 1862
- Hines' Raid, Location: Orange & Crawford counties, June 18, 1863
- Battle of Brandenburg Crossing, Location East of Mauckport, July 7, 1863
- Battle of Corydon, Location: Corydon, July 9, 1863