In Congress, violence was often deployed strategically. Representatives and senators who were willing to back up their words with their weapons had an advantage, particularly in the debate over slavery. Generally speaking, Northerners were least likely to be armed, and thus most likely to back down. Congressional bullies pressed their advantage, using threats and violence to steer debate, silence opposition and influence votes.
In 1842, Representative Thomas Arnold of Tennessee, a member of the Whig Party, learned the hard way that these bullies meant business. After he reprimanded a pro-slavery member of his own party, two Southern Democrats stalked toward him, at least one of whom was armed with a bowie knife — a 6- to 12-inch blade often worn strapped to the back. Calling Arnold a “damned coward,” his angry colleagues threatened to cut his throat “from ear to ear.” But Arnold wasn’t a man to back down. Ten years earlier, he had subdued an armed assassin on the Capitol steps.
Lots more at:
http://www.nytimes.com/2011/01/12/opinion/12freeman.html?src=me&ref=general