Why the North Fought the Civil War
By ERIC FONER
Published: April 29, 2011
Among the enduring mysteries of the American Civil War is why millions of Northerners were willing to fight to preserve the nation’s unity. It is not difficult to understand why the Southern states seceded in 1860 and 1861. As the Confederacy’s founders explained ad infinitum, they feared that Abraham Lincoln’s election as president placed the future of slavery in jeopardy. But why did so few Northerners echo the refrain of Horace Greeley, the editor of The New York Tribune: “Erring sisters, go in peace”?
The article is found here
http://www.nytimes.com/2011/05/01/books/review/book-review-the-union-war-by-gary-w-gallagher.html