Leroy C. McLaughlin finished his workday on Friday and was cooking dinner when a family member phoned. The 4-foot-by-8-foot Barack Obama campaign sign that McLaughlin had posted in the front yard of his Chesterfield County home was gone. A Confederate flag hung in its place. Surveying the scene that night, McLaughlin, 78, a Baptist minister and an Army veteran who lived to see the first black person nominated to a major-party ticket, had a message for whoever left the flag, viewed by many as a symbol of racial oppression: "I love you, and God does, too." That same night, someone...