History of the Peloponnesian War

During the night he bivouacked unobserved near the sanctuary of Hermes, about sixteen stadia distant from Mycalessus, but at daybreak assaulted the town, which was not large, and took it; for he fell upon the people off their guard and not expecting that anybody would ever march so far inland from the sea and attack them; furthermore, their wall was weak, and at some points had even fallen down, while elsewhere it had been built low, and at the same time the gates were open because of their feeling of security.

So the Thracians burst into Mycalessus and fell to plundering the houses and the temples and butchering the people, sparing neither old nor young, but killing all whom they met just as they came, even children and women, aye, pack-animals also and whatever other living things they saw. For the Thracian race, like the worst barbarians, is most bloodthirsty whenever it has nothing to fear. And so on this occasion:

in addition to the general confusion, which was great, every form of destruction ensued, and in particular they fell upon a boys' school, the largest in the town, which the children had just entered, and cut down all of them. And this was a calamity inferior to none that had ever fallen upon a whole city, and beyond any other unexpected and terrible.