The explanation of the peril and dissolution of the Union forms the theme of this chapter. Such calamitous events as Civil War had numerous causes, large and small, such as moral duties, sectional politics, growing apprehensions over emotional agitators, and a concern for freedom and independence on the part of blacks, white southerners, and western farmers. This chapter analyzes how the momentous issue of slavery disrupted the political system and eventually the Union itself. We will look at how four major developments between 1848 and 1861 contributed to the Civil War: first, a sectional dispute over the extension of slavery into the western territories; second, the breakdown of the political party system; third, growing cultural differences in the views and lifestyles of southerners and northerners; and fourth, intensifying emotional and ideological polarization between the two regions over losing their way of life and sacred republican rights at the hands of the other. A preview of civil war, bringing all four causes together, occurred in 1855-1856 in Kansas. Eventually, emotional events, mistrust, and irreconcilable differences made conflict inevitable. Lincoln's election was the spark that touched off the conflagration of civil war, with all its "train of horrors."