The Civil War re-enactor who died of a heart attack has been identified as Tim Landacre, 48, of Bridgeport, W.Va.
Landacre portrayed the color sergeant for the 49th Ohio Volunteer Infantry, according to the president of the re-enactor's group, Mark Holbrook, who posted a message to an Internet discussion group.
Landacre collapsed about 7 a.m. Sunday, during the Cornfield battle re-enactment.
"He died of a heart attack on the field he loved so much. While our hearts are heavy, we take comfort in knowing that the thoughts and prayers of so many are with us," Holbrook wrote.
Heart attacks are not unusual during re-enactments because of the physical stress involved, officials said.
Landacre attended the 135th Commemoration of the Battle of Antietam with his 13-year-old son, Washington County sheriff's deputies said.
The condition of a civilian re-enactor who was burned by a chemical explosion on Sunday improved on Monday.
Elizabeth Gibson of Rochester, N.Y., was in good condition at Washington Hospital Center in Washington, D.C., according to the hospital.