Olympic Teams: 2004
Senior World Championship Teams: 2012 (Gold - Team), 2011, 2010 (Silver - Team), 2009, 2007, 2006, 2005, 2003, 2001
Pan American Games Teams: 2011 (Gold - Team), 2007 (Bronze - Team)
Junior World Championship Teams: 2001
Personal: A silly debate ushered Mattern into fencing. He and his brother argued who would win if a musketeer fought a Samurai warrior; Mattern backed the musketeer. When a mutual friend mentioned he was taking fencing lessons at a nearby club, the boys seized the chance to follow up on their swordplay interests. His brother quit after about a year, but Mattern was hooked. He says the sport fits his personality perfectly because it is an individual sport, and also a "no-excuse sport." Though Ohio State and Notre Dame, among others, offered Mattern fencing scholarships, he decided to continue to train and work in Oregon. He is now a resident athlete at the Colorado Springs Olympic Training Center, and a part of the Army's World-class Athlete Program.