There is an interesting theory that Diocletian and Maximianus started to proclaim their relationship with Jupiter and Hercules because of the revolt of Carausius. It was "an attempt to impose a divine order on the administering of the Empire, a "cosmic unity" that would automatically exclude any usurper from a place within the Empire." (In Praise of Later Roman Emperors pg 48) It is impossible to prove, but an interesting idea.
see: William Seston "Dioclétien et la Tétrarchie"
