427 BC

Year 427 BC was a year of the pre-Julian Roman calendar. 

 Events 
 Sparta's King Archidamus II is succeeded by his son Agis II.
 Cleon says Mytilene must be destroyed. He decides not to kill the people.
 Plataea surrenders to the Spartans and Thebans. Over 200 prisoners are put to death and Plataea is destroyed.
 The civil war in Corcyra results in a victory of the democrats over the oligarchs.
 The Quaestorship is opened to the Plebs.

 Births 

 Plato, Greek philosopher (d. c. 347 BC)
 Xenophon, Greek historian, soldier, mercenary and an admirer of Socrates (d. 354 BC)

 Deaths 

 Archidamus II, king of Sparta