The Civil War started because both sides were tired of compromise. The Whigs and Democrats, were not really supporting the needs of the people, and were mostly there for their own selfish reasons. Politicians had quickly become seen as malignant and corrupt, which made people begin to lose faith in the Party System's ability to solve problems. Politicians were also seen as out of touch with their constituents as no side, Slave or Free were really winning the argument by the 1850's, the argument had only been postponed by a series of compromises such as the Missouri Compromise, the Compromise of 1850, and the Kansas Nebraska Act.
All of these had attempted to cool tensions between an enraged South, and an angry North. Not only did any of these compromises fail to do that, but the parties had lost the faith of the people who had elected them into power to accomplish a specific goal. For example, Stephen Douglas, who was seen as a "moderate" on slavery, supporting Popular Sovereignty in States, was rejected by the South as the Democratic Nominee in 1860 because the Southern Wing of the Democratic Party did not view Douglas as "pro slavery" enough. The people on both sides were simply tired of political compromise.
The politicians' failure to please their constituents lead to a rise of people creating new parties, such as the Republicans, to "fix Washington," or some people, like John Brown, merely took matters into his own hands and started killing people. Brown's attack on Harper's Ferry and subsequent execution heightened North-South tensions to an even higher level. People turned to violence because of the political system's inability to solve the Slavery issue.
It almost sounds like today. Not the whole details (as in Slavery, harpers ferry, etc) but the rise of new parties or political groups, the intense disdain for compromise on both sides of the aisle, the tension getting higher and higher between the two parties or ideals.
