The orator Lysias delivers his most important speech, “Against Eratosthenes,” written in 403 in prosecution of the man who had caused the execution of his brother. (Lysias’s most successful speeches, however, are those he writes for clients to deliver in the Athenian law courts. His speeches, of which thirty-four survive, will become the model of the "plain style" in the eyes of later students of rhetoric.)

Under the archon Euclides, Athens officially adopts the Ionian alphabet in 403 BCE. (Each Greek state has its own alphabet, but use the Ionian alphabet for capital letters. The standardized alphabet soon spreads throughout Greece.)

A small army of democrats under Thrasybulus marches south from Phyle to depose the reactionary Thirty and restore democratic rule, and Critias is killed in fighting in the Piraeus.

Lysander, sent to support the Thirty at Athens against Thrasybulus' democratic revolt, is nearly successful, but a reversal of policy in Sparta leads by the end of 403 to a settlement that allows the restoration of democracy at Athens.