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 beat a maid servant. She fled to the camp of Captain Moroni and told him of Morianton's plan. Captain Moroni quickly dispatched Teancum who heads off Morianton in his flight and, when he will not surrender, is forced to slay him.  

Alma 50