History of the Peloponnesian War
Thucydides
Thucydides. The history of the Peloponnesian War, Volume 1-2. Dale, Henry, translator. London: Heinemann and Henry G. Bohn, 1851-1852.
and if they did not obey, should make war upon them. So the ships set sail; but the ten triremes of the Mytilenaeans, which had come to them as a reinforcement, according to the terms of their alliance, were detained by the Athenians, and the crews of them were put in prison.
The Mytilenaeans, however, were informed of the expedition against them by a man who crossed over from Athens to Euboea, and having gone by land to Geraestus, there found a merchant-vessel getting under weigh, and so proceeded by sea, and arrived at Mytilene the third day after leaving Athens. Accordingly they both abstained from going out to the temple at Malea, and, for the rest, barricaded and kept guard around their half-finished walls.
When the Athenians sailed up soon after and saw this, the commanders delivered their orders; and as the Mytilenaeans did not obey them, they commenced hostilities.