Derdas II (Ancient Greek: Δέρδας) was the ruler of the region of Elimiotis (Ἐλιμιώτις), also rendered as Elymia (Ἐλιμία) and Elimeia (Ἐλίμεια), in the early 4th century BCE.
The Macedonian king Aëropus, who had usurped the throne in 398/7 died this year of an illness and was succeeded by his son Pausanias.
Aristotle, in a discussion of royal assassinations, said in his Politics:Any sort of insult (and there are many) may stir up anger, and when men are angry, they commonly act out of revenge, and not from ambition.
Sparta, having assumed responsibility for keeping the peace throughout Greece since defeating Athens in the Peloponnesian War, committed to the project of reining in Olynthus.
The Olynthians chose to attack the city before the Spartan army arrived, but as they approached the gates, Derdas counterattacked, routing them and chasing them all the way back to Olynthos itself.