Born in 1821 in South Carolina, James Longstreet graduated from West Point in 1842 and served with distinction in the Mexican War. As the officer corps split along sectional lines, he joined the Confederacy in 1861, eventually rising to join Gen. Robert E. Lee’s inner circle.

But it was after Appomattox that Longstreet truly distinguished himself — as the rare ex-Rebel to accept the South’s defeat, and its consequences. He urged fellow white Southerners to support the federal government and help rebuild their region on the basis of greater racial equality. He joined Abraham Lincoln’s Republican Party.

In the 1870s, he commanded a biracial state militia loyal to Louisiana’s Reconstruction government, aggravating an old war wound while fighting alongside his troops against violent white supremacists in the streets of New Orleans.

Today, this illustrious American is famous only to Civil War buffs. He remains obscure, even as the country struggles anew with the legacy of the Civil War and Reconstruction — from the removal of the Confederate battle flag at South Carolina’s state capitol, to this week’s flap over Hillary Clinton’s remark implying Lincoln’s successors were too “rancorous” toward the defeated South.

Yet ending Longstreet’s obscurity, and properly honoring him, can and should be a part of the discussion. Indeed, it’s hard to imagine a full and fair reckoning with the past in which such a personality gets no more than a footnote. ...