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.
When, however, after assaulting Oenoe, and trying every method, they were unable to take the place, and the Athenians sent no herald to them, then indeed they set out from before it, and about eighty days after the events at Plataea, caused by the Thebans who had entered it, when the summer was at its height, and the corn ripe, they made their incursion into Attica; Archidamus son of Zeuxidamus, king of the Lacedaemonians, being their commander.
After pitching their camp there, they first ravaged Eleusis and the Thriasian plain, and put to flight some Athenian cavalry near a place called Rheiti [or
the brooks]. Afterwards they continued their march, keeping Mount Aegaleos on their right through Cropaea, till they came to Acharnae, a place which is the largest of the demes, [or townships,] as they are called, of Attica. And sitting down before it they formed an encampment, and stayed a long time in the place, and continued ravaging it.
It was with the following views that Archidamus is said to have remained in order of battle at Acharnae, and not to have gone down to the plain during that incursion.
He hoped that the Athenians, abounding as they were in numbers of young men, and prepared for war as they had never before been, would perhaps come out against him, and not stand still and see their land ravaged.
Since, then, they had not met him at Eleusis and the Thriasian plain, he pitched his camp at Acharnae, and tried whether they would now march out against him.