TEOC, Miss. -- Lillie McCain is watching the presidential campaign from a singular perspective.

A 56-year-old psychology professor whose family spans five generations from the enslavement of her great-great-grandparents to her own generation's fight for civil rights, Ms. McCain appreciates the social changes that have opened the way for Sen. Barack Obama to be the first major-party black contender for the White House.

But she also has an uncommon view on another American passage. Ms. McCain and her siblings are descended from two of about 120 slaves held before the end of the Civil War at Teoc, the Mississippi plantation owned by the family of Republican nominee John McCain's great-great-grandfather.

In a year when the historic nature of Sen. Obama's candidacy is drawing much comment, the case of the Teoc McCains offers another quintessential American narrative in black and white. For the black McCain family, it is a story of triumph over the legacy of slavery; for the white McCains, it is the evolution of a 19th-century cotton dynasty into one rooted in an ethic of military and national service.