History of the Peloponnesian War
Thucydides
Thucydides, Vol. 1-4. Smith, Charles Foster, translator. London and Cambridge, MA: Heinemann and Harvard University Press, 1919-1923.
I will, however, explain to you in what way I intend to make the attack, in order that my plan of fighting in detachments and not in a body may not seem to anyone poor tactics and thus cause discouragement.
For I imagine that the enemy ascended the hill in contempt of us and because they could not have expected that anybody would come out for battle against them, and now, with broken ranks and intent upon reconnoitring, are taking small account of us.
Now when an assailant having most clearly observed such errors in the enemy also makes his attack in accordance with the force at his own disposal, not openly and in array of battle, but as may be advantageous under present circumstances, then he would be most likely to succeed.
And those. stratagems have won the highest credit by which a man most completely deceives the enemy and helps his friends.
While, then, the Athenians, still unprepared, are full of confidence and are thinking, so far as I can see, more of withdrawing than of staying where they are, while their tension of mind is relaxed and before they have got their thoughts together, I will take my own troops and if possible surprise them by a dash upon the centre of their army.