When it was repealed in the early 1850's, that's when we started on the true road to war. Had the Missouri Compromise been left alone - if the southern slave states hadn't used their congressional power to repeal it and again attempted the spread of slavery, there would have been no Civil War - but the slave powers didn't care about that. Although "State's rights" in the South were only important insofar as it involved the right to own slaves. Revisionist historians like to use "state's rights" as a way to defend the actions of secessionists, but outside of slavery secessionists cared very little about state's