The wool pants itch, especially around the inner thighs, especially when you're marching. The rifle's heavy. So's the canteen, kit and bayonet, which dig into your haunches. After a good hour of standing at attention and shifting stances in the militant summer sun, the tendons in your right arm burn, sweat slicks your back under the sack coat, and you might wonder, Why live like a Civil War soldier these days if you don't have to?

"Because they can't," says Ray Wetzel, 55, a resident of Hanover, Pa., and member of the 13th Pennsylvania Reserves, a reenactment unit that portrays those Union infantrymen. He's referring to the hundreds of thousands who served and died during the Civil War. They're not around to remind us, Wetzel says, but he is.

And so are hundreds of other reenactors in the District, Maryland and Virginia, especially now that we're in the thick of reenactment season in an area swollen with Civil War battlefields. More than 3,000 reenactors will invade south central Pennsylvania on Friday for the Annual Gettysburg Civil War Battle Reenactment, just as 80 reenactors did in Westminster, Md., last weekend for a commemoration of Corbit's Charge, one of the small but consequential conflicts that paved the way for that tide-turning battle.