In the stormy aftermath of the old noble council losing its powers, Pericles' ally, Ephialtes, was assassinated. It was a dangerous time for the budding leader as Cimon, the pro-Spartan politician who had probably organized the ostracism of Themistocles ten years before in 470, tried to re-assert himself as Athens' foremost politician.

But Cimon underestimated the power of the common people and was ostracised. As a result Pericles now joined the front rank of Athenian politicians. Over the next ten years he led several important military expeditions, helped reinforce Athens' control over the naval alliance called the Delian League, approved a final peace with Persia, and introduced payment for jury service. This last act marked a major step forward for the poor, since they too could now afford to take time off their normal work to become involved in politics.

Athenian democracy was entering its most radical phase...