After Mytilene's revolt fails, the Athenian assembly orders all its men killed. The next day it debates again and sends a second ship to stop the order.
The morrow brought repentance with it and reflection on the horrid cruelty of a decree, which condemned a whole city to the fate merited only by the guilty.
A second ship arrived just in time, the massacre was prevented and the people of Mytilene were spared. Thucydides' record of the debate gives important insight into Athenian democracy and imperial policy.
Based on Wikipedia: Mytilenean Debate
Favorable weather and diligence of the rowers ensured that the second trireme arrived just in time; Paches had only just read the decree brought by the first trireme but had not yet carried out the sentence.
The massacre was prevented and the people of Mytilene were spared.
The debate as recorded by Thucydides provides important insight into Athenian democracy and imperial policy, and reflections upon their development and role in the Peloponnesian War.