The Slickers were organized to rid the county of thieves and counterfeiters.   The name of the organization came about because they would tie the culprit to a tree and “slick” or whip him with hickory sticks. He was then given notice to leave the country within a stated time.   The first Slicker organization in Missouri started in Benton County.  At times, false reports were made and people were unjustly accused.  This led to the organization of the anti-Slicker companies, and in some parts of the State actual war raged between the opposing factions, and many persons were killed, wounded, or maltreated. 

A complete account of the Slickers can be found here:

http://www.hearthstonelegacy.com/the-slicker-wars-missouri.htm