So some residents brought food, water and medical supplies for the wounded, she said.
"Most people helped whomever they would find," whether they were Confederate or Union, she said.
Civil War historian and Antietam Commemoration Committee Co-chairman Dennis Frye said it was rare that a local citizen would go on the real battlefield.
"When they began to fight, the local people got as far away as possible," Frye said.
At Friday's re-enactment of the Battle at Fox's Gap, two civilian re-enactors were overheard cheering on the Confederates to shoot the Yankees. Frye wasn't aware of spectators at the real battle cheering for one side or the other.
"People weren't stupid," Frye said. "They could have ended up in the way of a bullet that wasn't meant for them."
Ernst said there was a tale of a local man cheering on the Union.
William Roulette's family hid in the cellar for most of the battle, but Roulette eventually had to come up and see the fighting, Ernst said. A Union sympathizer, Roulette saw Confederates on his farmland.
Waving his hat, Roulette supposedly yelled to the Union troops to "Drive them, drive them. Take anything you want on my place" to get the Rebels off his land, Ernst said.