A few weeks before Captain George S. James sent the first mortar round arcing through the predawn darkness toward Fort Sumter, South Carolina, on April 12, 1861, Abraham Lincoln cast his Inaugural Address as a last-ditch effort to win back the South. A single thorny issue divided the nation, he declared: "One section of our country believes slavery is right and ought to be extended, while the other believes it is wrong and ought not to be extended. This is the only substantial dispute."
It was not a controversial statement at the time. Indeed, Southern leaders were saying similar things during those fateful days. But 150 years later, Americans have lost that clarity about the cause of the Civil War, the most traumatic and transformational event in U.S. history, which left more than 625,000 dead more Americans killed than in both world wars combined.
Shortly before the Fort Sumter anniversary, Harris Interactive polled more than 2,500 adults across the country, asking what the North and South were fighting about. A majority, including two-thirds of white respondents in the 11 states that formed the Confederacy, answered that the South was mainly motivated by "states' rights" rather than the future of slavery.
The question "What caused the Civil War?" returns 20 million Google hits and a wide array of arguments on Internet comment boards and discussion threads. The Civil War was caused by Northern aggressors invading an independent Southern nation. Or it was caused by high tariffs. Or it was caused by blundering statesmen. Or it was caused by the clash of industrial and agrarian cultures. Or it was caused by fanatics. Or it was caused by the Marxist class struggle.
On and on, seemingly endless, sometimes contradictory although not among mainstream historians, who in the past generation have come to view the question much as Lincoln saw it. "Everything stemmed from the slavery issue," says Princeton professor James McPherson, whose book Battle Cry of Freedom is widely judged to be the authoritative one-volume history of the war. Another leading authority, David Blight of Yale, laments, "No matter what we do or the overwhelming consensus among historians, out in the public mind, there is still this need to deny that slavery was the cause of the war."