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.
And when the whole army was assembled, Archidamus, the king of the Lacedaemonians, who was to be the leader of this expedition, called together the generals of all the states as well as the chief officials and the most notable men, and exhorted them as follows:
" Peloponnesians and allies, our fathers made many campaigns both in the Peloponnesus and beyond it, and the elder men also amongst us do not lack experience in warfare, yet never before have we taken the field with a greater armament than this; but though we were never more numerous and puissant, it is also a very powerful state we now go against.
It is but right, therefore, that we neither should show ourselves worse men than our fathers nor wanting to our own fame. For all Hellas is stirred by this enterprise of ours, and fixes her gaze upon it, and being friendly to us on account of their hatred of the Athenians hopes that we shall succeed in carrying out our designs.
Therefore, even if some of us may think that we are going against them with superior numbers and that in all likelihood the enemy will not risk a pitched battle with us, we must not on that account be a whit less carefully prepared when we advance, but rather must officer and soldier of every state for his own part be always expecting to encounter some danger.
For the events of war cannot be foreseen, and attacks are generally sudden and furious; and oftentimes a smaller force, made cautious by fear, overmatches a larger number that is caught unprepared because it despises the foe.