Sparta suffers the effects of a severe earthquake leading to a large loss of life.
When the Messenian helots (serfs) revolt against their Spartan masters following the severe earthquake, King Archidamus II organises the defence of Sparta. The helots fortify themselves at Mount Ithome.
Persian empire
Egypt seizes the opportunity created by the murder of Xerxes I to revolt against Persia. The revolt is led by Inaros, a Libyan.
Artaxerxes I succeeds Xerxes as king of the Persian empire.