I assume that you are talking about the crisis in Kansas during the time just before the Civil War. This is a time or incident that is often referred to using the term "Bleeding Kansas."
Because of the Kansas-Nebraska Act of 1854, Kansas was going to get to vote on whether it wanted to be a free territory or a slave territory. What this led to was partisans of both sides trying to make sure they had a majority in the territory before the vote happened. This often led to acts of violence against the other side -- there were infamous massacres committed by people on both sides.
So, this was a crisis in which violence and other means were used to try to get a majority in Kansas for either the pro-slavery or the anti-slavery side.