Arnold completed an impressive career in the Missouri National Guard that spanned more than four decades, before retiring in 2009. He was a First Sergeant in four different companies and served with 21 different company commanders during his time as a first sergeant. During his career, Arnold earned 11 different MOSs and served during 11 State Emergency Duties. In 1975, was awarded the Missouri Conspicuous Service Award for battling a large fire at Camp Clark in a large storage building and equipment storage area by removing a large amount of equipment, thus preventing it from being lost in the fire. Arnold worked full-time for the National Guard at Camp Clark in the Maintenance shop for 35 years, retiring as the Shop (Chief) Supervisor.