Anonymous had the right answer. We were at Prophetstown State Park near Lafayette. After our group finished with the Feast of the Hunter's Moon, we headed over to the campground at Prophetstown and set up camp. We all ate supper in the light rain, but only half the group stayed over night. The other half, which included me, came back to Rensselaer.
nice article on the Delphi trail system.
Update 2: November 5-7 will mark the bicentennial of the Battle of Tippecanoe. Programs are planned for both Prophetstown State Park and the Battlefield Memorial. Detail can be found here.