Holt might have enjoyed spending time with his friends but he also was serious about the work.
"It's quite humbling being here," Holt said. "Even though they are just a bag with a candle and some sand in it, it represents a human life, and although one bag doesn't do a very good job, the sight of all of those candles represents the sacrifice all these people made to fight for what they thought was right ... that touches me."
After darkness falls, the candles glow throughout the park.
"It's a beautiful finish to such a boring and menial task initially," Holt said. "I feel a lot smaller when I'm here."
One of Holt's schoolmates, 15-year-old Anna Beckett, was struggling to keep her lighter warm in the sub-freezing temperatures Saturday afternoon.
Beckett, who lives in Shepherdstown, W.Va., had seen the Illumination driving by the battlefield and on television, so she signed up when her school was looking for volunteers.
"It's cold, but it looks really cool when you're all finished," she said.
She didn't know much about Antietam's history, but "I know hundreds and thousands of people died," she said.
Illumination organizers have a waiting list of people who want to volunteer, said John Howard, Antietam National Battlefield superintendent.
The volunteers arrive at about 8 a.m. and get all of the work - setting out the bags, then lighting them - finished by 4 p.m., he said.
Volunteers come from across Maryland, southern Pennsylvania and Virginia, Howard said.
This year, volunteers came from Connecticut and New Jersey, said Georgene Charles, chair of the memorial illumination.
Dennis Bailey left his home in Severn, Md., at 6:30 a.m. Saturday to arrive at the park when work started at about 8:30.
Bailey has been volunteering for the illumination with other members of his Knights of Columbus chapter for four or five years, he said.
"It's some way to remember these guys," he said. "The struggle they had to keep this nation together."
Saturday was the first time Pam and Mike O'Brien of Silver Spring, Md., worked at the illumination. Both enjoy Civil War-period history and were on hand Saturday for a portion of the illumination ceremony that honored troops currently serving.
The O'Briens' son-in-law, Lt. Seth Dvorin, died in Iraq in February 2004.
"As you're working the bags and lighting them, you get a sense of what you're doing," Pam O'Brien said.
He enjoyed the "great spirit" of the day and being part of a community effort, Mike O'Brien said.
Howard mentioned several people who have volunteered their time to the illumination each of its 20 years.
One of those volunteers, Kevin Graff, was chosen to say a few words.
Graff called the illumination "one of the most important displays to honor brave men that I have ever witnessed."
He hoped younger generations were inspired to remember and honor history, Graff said.
But some improvements could be made.
His first suggestion?
"Like the television shows, let's start taping this in the summer," he said.