"Believe me, if you get hit in the head with one of these, a couple Tylenols are not going to help," Kerling told the crowd.
Kerling and his troops then fired some blank rounds off, and marched in formation to a drumbeat to the crowd's pleasure.
The demonstration was one of many learning experiences at the park Saturday. Period musicians, actors and merchants at the park dressed in clothing from the late 1700s, making for a fun and educational activity.
Hundreds visited the park Saturday for the 11th annual 18th Century Market Fair.
Marc Robinson, 45, of Bunker Hill, W.Va., and his nephew Roark Robinson, 10, of Hagerstown, watched the military demonstration with interest.
Marc Robinson said he is interested in colonial history, and wanted to take the chance to buy some period items. He was carrying a wooden club with a bone edge.
Roark Robinson said he enjoyed seeing how people dressed differently, especially some people who had dressed as Native Americans.
Stephen Vincenti, 48, traveled from the Pittsburgh area to Fort Frederick. Dressed as a period fighter himself, he was there to buy some items to outfit his wardrobe.
Vincenti said he enjoys taking part in events such as Saturday's for "the history and the memories, and some new friends that I meet."
Phil Woodberry, 58, also was dressed as a period soldier. He is the captain of the Joshua Bells Company, which is the marching troop based in Fort Frederick, the same one that Kerling was marching with.
Woodberry said he has been working with the historical group for 30 years. He said he often finds that the French and Indian War is forgotten. The fort was active during the war, and Woodberry said he aims to help people learn more about the era.
"If it wasn't for the French and Indian War, we'd be speaking French," Woodberry said.
But the most important part of his work at the fort, Woodberry said, is "to have fun, and we do."