WASHINGTON - Army Staff Sgt. Mark Pheabus puts on his uniform every month to train with the Maryland National Guard's 29th Military Police Company in Westminster, Md.
This weekend, however, he'll be wearing a very different uniform, portraying a Confederate soldier at reenactments marking the 150th anniversary of the Battle of Antietam.
Days after Americans observed the 11th anniversary of the 9/11 attacks on the United States, Pheabus will be among thousands gathering in Sharpsburg, Md., to commemorate the bloodiest single day in U.S. history.
Antietam was the first major Civil War battle to take place on Northern soil. It pitted Robert E. Lee's Army of Northern Virginia against George B. McClellan's Army of the Potomac at Antietam Creek.
The 12-hour battle on Sept. 17, 1862, claimed a mind-boggling 23,000 casualties among Union and Confederate forces. That's more troops killed, wounded and missing than during the Revolutionary War, the War of 1812 and the Mexican War combined.
The 150th commemoration, which kicks off today at Antietam National Battlefield and continues through the weekend, will include reenactments and a wide variety of forums, tours and lectures to help educate the public about the battle.
It also will include a candle-lit remembrance ceremony. The names of all 2,108 Union and 1,546 Confederate soldiers that were killed or mortally wounded in the battle will be read aloud, followed by an artillery salute.
For Pheabus and his fellow reenactors, participating in the battle's 150th anniversary "is a very big deal," he said.
A history buff since childhood who grew up fascinated by the Civil War, Pheabus participated in his first reenactment in the mid-1970s. After a hiatus due to conflicts with his military drill weekends, he returned to the hobby several years ago.
Pheabus has portrayed both Union and Confederate soldiers, as well as civilians on the battlefield. "I have all the uniforms, equipment and camping gear," he said.
This weekend, however, he'll be a member of Lee's army, which some historians say technically won the battle. However, McClellan had halted Lee's invasion of the North.
And though Lee's troops had held their ground at the end of the bloody day, the Confederates were so depleted that they had to limp back to Virginia, making it a less-than-overwhelming victory.
The outcome could have been markedly different, Pheabus recognizes.
Many of Lee's forces were underequipped, the result of an uneven distribution system that left some Confederate states with packed warehouses and others with nothing.
In addition, Lee lost about one-third of his army at the Potomac River crossing. Many of the Confederates were focused only on defending their homes and saw no reason to press into Maryland and points further north.
McClellan had a big advantage going into the battle. One of his soldiers, a corporal from the 27th Indiana troop, had found Lee's battle plan in a field, wrapped around three cigars.
McClellan's army also outnumbered the Confederates almost two-to-one, but the Union general kept many of his soldiers in reserve rather than committing them to the battle.
"Lee's army could have been destroyed right there if McClellan hadn't been so timid," Pheabus said.
Historians are mixed on that point. In a recent presentation for the Defense Department's historical speakers' series, retired history professor Tom Clemens said McClellan, considered by many historians to be an ineffectual commander, was in fact hamstrung by political and military jealousies that ultimately led to his removal from command.
Although the 150th anniversary commemoration will focus on the battle and its impact on the Civil War's outcome, Pheabus said he's looking forward to bringing alive the stories of the soldiers who fought it. In many cases, he said they're just like today's men and women in uniform.
"They have so much in common," he said. "They were all away from home, missing their families. It's everything that our soldiers experience now."
Although the Battle of Antietam is remembered for its human toll, historians note that it proved to be transformational -- for the United States and the U.S. military.
A week after the battle, President Abraham Lincoln issued the Emancipation Proclamation that freed slaves held in Confederate territory, but ironically, not those in Maryland. That order took effect Jan. 1, 1863.
Lesser recognized by many are the new doors the Battle of Antietam helped open for the armed forces. It laid the foundation for today's military medical system and its logistics network and led to the founding of the American Red Cross, the Christian Commission and other nonprofit organizations supporting the military.
The tactics of the battle continue to be studied today and analyses of them will not only fill volumes, but libraries. Historians attribute the heavy human toll at Antietam to Napoleonic doctrine and tactics – with concentrated forces, rank-and-file battle formations and close-quarters combat -- along with artillery, improved rifles and "Minie ball" ammunition that caused massive internal damage.
The magnitude of the carnage proved to be a test bed for the newly organized Union Ambulance Corps that evacuated casualties from the battlefield. Troops too wounded to be moved were treated for the first time in new, semi-permanent field hospitals.
And despite their differences, Union and Confederate soldiers were treated side by side, receiving the same level of care from the Union Medical Department. "Humanity teaches us that a wounded and prostrate foe is not then our enemy," remarked Dr. (Maj.) Jonathan Letterman, medical director for McClellan's army.
Letterman was a visionary in other ways as well, and is remembered today as the "Father of Modern Battlefield Medicine."
He took lessons from Antietam and other Civil War engagements to develop a medical evacuation system that transported casualties to a field dressing station, then a field hospital, then to a large field hospital away from the battlefield.
And frustrated by delays in getting medical supplies where and when they were needed, Letterman came up with an efficient distribution system that ensured regiments had ready access to basic medical supplies and a reliable source of replacements.
Meanwhile, another Civil War luminary, Clara Barton, provided surgeons with critical medical supplies, fed and comforted the wounded, and even helped surgeons during operations.
Remembered as the "Angel of the Battlefield," Barton took her experiences at Antietam and elsewhere during the Civil War to found the American Association of the Red Cross in 1881. She also established what became the Missing Soldiers Office, which helped to locate more than 22,000 missing soldiers after the war.
Another nongovernmental organization, the U.S. Christian Commission, gained a strong following after the battle. Created by leaders of the Young Men's Christian Association and Protestant ministers, it rallied to provide medical, recreational and religious support for Union troops.
Antietam also introduced the horror of war to many Americans through the combat photography of Matthew Brady, Alexander Gardner and his assistant, James Gibson.
"If he has not brought bodies and laid them in our dooryards and along streets, he has done something very like it," The New York Times wrote of Brady's "The Dead of Antietam" exhibit.