The most stormy convention in U.S. history was held in Charleston, South Carolina, in April 1860. The Democrats were already deeply divided over the issue of slavery, and there was little effort to seek any sort of compromise. Indeed, there were 27 roll calls over procedural matters before the meeting even began.
When it came to voting on the slavery plank in the party platform, 45 Southern delegates from nine states stormed out in protest. They insisted that no state government should be able to outlaw slavery, but this plank was rejected.
Without them, no presidential candidate was able to get the required two-thirds majority to secure the nomination. After three days and 57 roll calls, the entire convention was adjourned; it reconvened two months later in Baltimore, where Stephen Douglas was eventually chosen as the presidential nominee. The disaffected southern Democrats held their own convention and nominated separate candidates, a schism that was a precursor of the Civil War.