He led a group of dissenters to take possession of the land northward thereby surrounding the Nephites with enemies.   He was defeated when he let his temper get the better of him and sorely beats a maid servant. She flees to the camp of Captain Moroni and tells him of Morianton's plan. Captain Moroni quickly dispatches Teancum who heads off Morianton in his flight and, when he will not surrender, is forced to slay him.  

Alma 50