Tomorrow marks the 150th anniversary of South Carolina's secession from the Union. Charleston's place as the setting of that historic event and of the fateful firing on Fort Sumter less than five months later forever mark this city as center stage for the Civil War's start.

And as our community, state and nation mark the sesquicentennial of disunion Monday, we start a four-plus-year process of solemn, insightful reflection on our nation's deadliest conflict.

Fifty years ago, the centennial of the war's local origin was largely celebrated here with pro-Confederate zeal. This time around, a more balanced approach stresses commemoration over celebration as the Fort Sumter-Fort Moultrie Historical Trust strikes a suitable sesquicentennial tone of "respect and honor."

Also appropriate is Charleston Mayor Joe Riley's invitation to President Barack Obama to participate in the Fort Sumter remembrance by narrating composer Aaron Copland's "Lincoln Portrait" during a commemorative concert on April 11 at White Point Garden.

That would be a proper role for any U.S. president. It's particularly fitting for this one, the son of a black man from Kenya and a white woman from Kansas. Mr. Obama's election to our nation's highest office debunks stale denials of remarkable progress in racial attitudes across our land.

Yet occasionally bitter debate endures over the war's causes, conduct and consequences. Demonstrating that lingering division are such competing titles as the War for Southern Independence, the War for the Union, the War of Northern Aggression and the War for Freedom.

But whatever you call what most of us call the Civil War, there's no call to blame anybody alive today for what anybody did in those old times not forgotten. As Frank Wooten writes on today's Commentary page, if the local blood kin of Preston Brooks and Charles Sumner can get along with each other, so should the rest of us.

The Civil War wasn't just a wrenching national tragedy. It was a defining ordeal that transformed the United States from plural noun (the United States are) to singular (the United States is).

E pluribus unum: Out of many, one.

And President Obama is not the only positive symbol of U.S. racial progress. Our historic city has come a long way on that front, too.

So as Charleston stars in the sesquicentennial's opening acts, take pride in how far we've come in the last 150 years. Take heed of how foolish it is to carry 150-year-old grudges.

And take note that though Mr. Riley has a remarkably long tenure as our mayor, he did not hold that office during the Civil War.