In 1838, Congressman William Graves of Kentucky shot and killed Congressman Jonathan Cilley of Maine in a duel over words spoken during a debate on the House floor.
Perhaps most notoriously, Congressman Preston Brooks in 1856 beat Senator Charles Sumner with a cane, right on the Senate floor. Althought the House's attempt to expel Rep. Brooks ultimately failed, he decided to resign his seat anyway.
The caning story is well-known but here's the kicker: Rep. Brooks, the guy with the cane who nearly beat Senator Sumner to death, went on to win his next election.
It seems at least in politics, sometimes incivility pays.