Antiochus I Soter
Towards the end of this series, a small wreath appears on the reverse to the left of Zeus. The wreath was a Greek symbol of victory. Frank Holt suggests that it commemorated a victory over the Parthians and that this victory was also the source of Diodotus' epithet "soter" (savour). Other Hellenistic kings, such as Antiochus I Soter and Attalus I Soter of Pergamum took this title to commemorate victories over existential barbarian threats. Diodotus may have done the same. This may further have been the occasion of Diodotus I's assumption of the royal title of king ("basileus")—as a similar victory was for Attalus I.