In Western Maryland is a stream called Antietam Creek. Nearby is the quiet town of Sharpsburg. The scene is pastoral, with rolling hills and farmlands and patches of woods. Stone monuments and bronze tablets dot the landscape. They seem strangely out of place. Only some extraordinary event can explain their presence.

Almost by chance, two great armies collided here. Gen. Robert E. Lee’s Army of Northern Virginia was invading the North. Maj. Gen. George B. McClellan’s Army of the Potomac was out to stop him. On September 17, 1862—the bloodiest day of the Civil War—the two armies fought the Battle of Antietam to decide the issue.

Their violent conflict shattered the quiet of Maryland’s countryside. When the hot September sun finally set upon the devastated battlefield, 23,000 Americans had fallen—nearly eight times more than fell on Tarawa’s beaches in World War II. This single fact, with the heroism and suffering it implies, gives the monuments and markers their meaning. No longer do they presume upon the land. Rather, their mute inadequacy can only hint of the great event that happened here—and of its even greater consequences.