The origins of the war were rooted in the desire of the
Southern states to preserve the
institution of slavery. Historians in the 21st century overwhelmingly agree on the centrality of slavery in the conflict—at least for the Southern states. They disagree on which aspects (ideological, economic, political, or social) were most important, and on the
North's reasons for refusing to allow the Southern states to secede. The pseudo-historical
Lost Cause ideology denies that slavery was the principal cause of the secession, a view disproven by historical evidence, notably some of the seceding states' own
secession documents. After leaving the Union, Mississippi issued a declaration stating, "Our position is thoroughly identified with the institution of slavery—the greatest material interest of the world."