"To me, this is like the Super Bowl of all re-enactments, not just this year," said Tom Bingham, 35, a Union re-enactor from Manchester, Conn.
The event was similarly praised by many others, but the first day was not without its glitches, as traffic slowly snaked into the Rench Road event site and spectators showed some confusion about when and where some events were being held.
Still, organizers considered the day a great success, especially when the skies cleared and temperatures rose to a beautiful 80 degrees after several days of clouds and rain.
"I'm ecstatic. This break in the weather is wonderful," said Greg Larsen, the event coordinator.
The re-enactment is being produced by the Association for the Preservation of Civil War Sites, which is headquartered in Hagerstown.
The weekend, which is being billed as the largest staged tourism event in the county's history, drew 7,000 spectators Friday, including hundreds of school children who were admitted free.
"This is the slow day. Imagine what (Saturday) is going to be like," Larsen said.
Event organizers had estimated as many as 30,000 spectators today, and a total of 50,000 for the entire weekend.
What was just a few days earlier 612 acres of farmland south of Hagerstown was transformed into a "city" of military and civilian re-enactors, spectators, food and souvenir vendors, and row upon row of white canvas tents.
Throughout the day military bands played and soldiers drilled. The air was filled with the smells of burning camp fires and black-powder smoke.
The highlights of the day were two battle demonstrations involving a few thousand re-enactors - a small preview of the re-enactments of actual Antietam battles today and Sunday.
"I think it's really amazing," Steve Kellogg, 48, who lives near Boston, Mass., said as rifles fired just a few feet away from him. "I gather this is rather small compared to what's going to happen in the next couple of days."
"It's interesting. You kind of want to go back in time," said Josh Spreng, a 15-year-old student at St. Maria Goretti High School in Hagerstown.
But while an afternoon battle demonstration was taking place, many of the spectators had mistakingly settled on a hillside far away, thinking the battle was to be held in front of them.
The problem, they said, was that there were no signs or event officials to direct them to the correct site, and the schedule of events pamphlet did not show the location of the battle.
"We don't know what is happening or where it is happening," said Harry Gode of Middletown, Md.
His wife, Claudia, said she is concerned the logistical breakdown might discourage people from attending today and Sunday. The couple is planning to return both days.
"It's very confusing," she said.
Larsen acknowledged there was some confusion in letting people know where the demonstration was taking place.
"We seemed not have succeeded as well as we should have in that," he said.
Many re-enactors applauded the organizers for their handling of the camps, which were still covered Friday with cars and trucks dropping off tents and other equipment.
"As far as setup, I think they've done a good job with what they have," said Joe Williams, 41, a Union re-enactor from Leonardtown, Md.
The Antietam re-enactment is considered to be the largest event of its kind this year, and possibly the largest ever. For that reason, many re-enactors said they were willing to put up with some last-minute changes and glitches.
"You don't get your expectations up too high with something this large, but I've been impressed," said Jeff Watkins, 18, a Confederate re-enactor from Akron, Ohio.
Friday's big crowd was a hit with many of the nonprofit organizations that were selling food at the event. The North Hagerstown High School Sports Boosters booth opened at 5:30 a.m. for breakfast and remained busy throughout the day.
"We've been swamped all day," said Buddy Knepp, vice president of the boosters.
First-aid officials said they treated several participants and spectators for blisters and mild dehydration, but there were no serious illnesses or injuries.