Jason of Pherae is the ruler of Thessaly during the period just before Philip II of Macedon coms to power.

He had succeeded his father Lycophron I of Pherae as tyrant of Pherae and was appointed tagus, or king, of Thessaly in the 370s BCE and soon extends his control to much of the surrounding region.

Controlling a highly trained mercenary force as well as the famous Thessalian cavalry, Jason briefly transforms Thessaly into a powerful Greek state and even speaks of invading the Persian Empire.

Before writing to Philip II, Isocrates sent letters to Jason requesting that he unify Greece, as Philip later would.

The figure of Jason makes a sudden appearance in the history of classical Greece with Xenophon swiftly mentioning his name during his commentary on Theban hegemony during the 370s.

From seemingly out of nowhere had arisen a very ambitious proto-Philip general with a hugely competent army.

Whether or not Jason had ambitions to rule over the entire Greek peninsula- as Philip II would after Chaeronea- can only be left to speculation.

Regardless, Jason epitomizes how one autocrat could suddenly rise to power through mercenary employment and threaten, both politically and militarily, his neighboring poleis.

Jason however is assassinated in 370, so one can only speculate on his political and military ambitions.

His son, Alexander, inherits the title of tagus and rules harshly before finally being defeated by the Thebans.