About 20,000 people attended the original dedication. About 700 attended Saturday's rededication, said J. Thomas Stouffer, of Sharpsburg, co-chairman of the Antietam National Cemetery.
The cornerstone to the U.S. Soldier's Monument in the center of the battlefield was laid by the Masons, following centuries-old tradition.
High ranking Masons recreated the ritual, somberly measuring the cornerstone with a level, a plumb and a square.
They also ceremoniously poured corn, wine and oil over the cornerstone. Worshipful Grand Lecturer Edward Kraft of the Grand Lodge of Maryland said the grain represents plenty, the wine represents health and the oil represents peace.
He said the Masons have traditionally set the cornerstones for public buildings and monuments.
The ceremony ended suddenly when a 94-year-old Mason, Lunda W. Laird, assistant grand chaplain, passed out in the heat.
His head hit against the stone with a sickening crack. However, Laird revived as fellow Masons got him water and fanned him to cool him. A Sharpsburg ambulance took him to Washington County Hospital for treatment.
Chuck Joseph, 39, of Wheaton, Md., dressed in the period clothes of a civilian in the 1860s. In addition to being an officer at his Masonic lodge, he does historical interpretation at Antietam National Battlefield.
"For me it was a nice combination of my Masonic involvement and my historic interest," Joseph said.
Dennis Jester Sr., 42, of Pasadena, Md., brought some members of a Cub Scout pack to watch the service.
"It's a beautiful setting up here," Jester said.
President Andrew Johnson and numerous representatives from across the country as well as ambassadors from Prussia, France and Mexico attended the cemetery's original dedication.
German ambassador Ulrich Locherer from the embassy in Washington attended yesterday's event, playing the role of the Prussian ambassador.
Maryland Gov. Parris Glendening was scheduled to attend, but was unable to because of work he was doing with the Pocomoke River's Pfiesteria piscicida outbreak, Stouffer said.