Walz enlisted in the Army National Guard in Nebraska in 1981 and retired honorably in 2005 as the top enlisted soldier for 1st Battalion, 125th Field Artillery Regiment, in the Minnesota National Guard, according to a copy of his records provided by the Minnesota Guard. He reached the rank of command sergeant major and served in that role, but he officially retired as a master sergeant for benefits purposes because he didn't finish a required training course, according to the records and a statement from the Minnesota Guard.