Spartans and Athenians Overthrow Hippias
In 510, Spartan troops helped the Athenians overthrow their king, the tyrant Hippias, son of Peisistratos.
Cleomenes I, king of Sparta, put in place a pro-Spartan oligarchy headed by Isagoras. But his rival Cleisthenes, with the support of the middle class and aided by democrats, managed to take over. Cleomenes intervened in 508 and 506, but could not stop Cleisthenes, now supported by the Athenians. Through his reforms, the people endowed their city with isonomic institutions (i.e. ones in which all have the same rights) and established ostracism.
Hippias of Athens (Ancient Greek: Ἱππίας ὁ Ἀθηναῖος) was one of the sons of Peisistratus, and was tyrant of Athens in the 6th century BC.
Hippias succeeded Peisistratus in 527 BC, and in 525 BC he introduced a new system of coinage in Athens. His brother Hipparchus, who may have ruled jointly with him, was murdered by Harmodius and Aristogeiton (the Tyrannicides) in 514 BC. Hippias executed the Tyrannicides and became a bitter and cruel ruler.
With help from the Alcmaeonidae (Cleisthenes' genos, "clan"), Cleisthenes was responsible for overthrowing Hippias, the tyrant son of Pisistratus. After the collapse of Hippias' tyranny, Isagoras and Cleisthenes were rivals for power, but Isagoras won the upper hand by appealing to the Spartan king Cleomenes I to help him expel Cleisthenes. He did so on the pretext of the Alcmaeonid curse. Consequently, Cleisthenes left Athens as an exile, and Isagoras was unrivaled in power within the city. Isagoras set about uprooting hundreds of people from their homes on the pretext that they too were cursed, and attempted to dissolve the council. However, the council resisted, and the Athenian people declared their support of it. Hence Isagoras and his supporters were forced to flee to the Acropolis, remaining besieged there for two days. On the third, they fled and were banished. Cleisthenes was subsequently recalled, along with hundreds of exiles, and he assumed leadership of Athens