Nice article in the Smithsonian Magazine on the beginning of the war - the entire article can be found here:
http://www.smithsonianmag.com/history-archaeology/Fort-Sumter-The-Civil-War-Begins.html
Generations of historians have argued over the cause of the war. “Everyone knew at the time that the war was ultimately about slavery,” says Orville Vernon Burton, a native South Carolinian and author of The Age of Lincoln. “After the war, some began saying that it was really about states’ rights, or a clash of two different cultures, or about the tariff, or about the industrializing North versus the agrarian South. All these interpretations came together to portray the Civil War as a collision of two noble civilizations from which black slaves had been airbrushed out.” African-American historians from W.E.B. Du Bois to John Hope Franklin begged to differ with the revisionist view, but they were overwhelmed by white historians, both Southern and Northern, who, during the long era of Jim Crow, largely ignored the importance of slavery in shaping the politics of secession.
Fifty years ago, the question of slavery was so loaded, says Harold Holzer, author of Lincoln President-Elect and other works on the 16th president, that the issue virtually paralyzed the federal commission charged with organizing events commemorating the war’s centennial in 1961, from which African-Americans were virtually excluded. (Arrangements for the sesquicentennial have been left to individual states.) At the time, some Southern members reacted with hostility to any emphasis on slavery, for fear that it would embolden the then-burgeoning civil rights movement. Only later were African-American views of the war and its origins finally heard, and scholarly opinion began to shift. Says Holzer, “Only in recent years have we returned to the obvious—that it was about slavery.”
As Emory Thomas, author of The Confederate Nation 1861-1865 and a retired professor of history at the University of Georgia, puts it, “The heart and soul of the secession argument was slavery and race. Most white Southerners favored racial subordination, and they wanted to protect the status quo. They were concerned that the Lincoln administration would restrict slavery, and they were right.”