The sound and smell of the brutal cannon barrages at the Battle of Fredericksburg must have been overwhelming. The deep, rich booming of the 12-pound, smoothbore Napoleons. The high-pitched "crack, crack" of Parrott rifles. And the acrid, sulfuric stench of black powder at each explosion. "A chicken could not live on that field when we open on it," said a Confederate cannoneer atop Marye's Heights to Lt. Gen. James Longstreet as they looked down upon advancing wave after wave of blue-coated Union soldiers. Soon, visitors to the Fredericksburg and Spotsylvania National Military Park will get a taste of what it...