History of the Peloponnesian War

But the Peloponnesians, when they found it out, took clay and therewith daubing hurdles of reeds cast the same into the chink, which mouldering not, as did the earth, they could not draw it away.

The Plataeans, excluded here, gave over that plot, and digging a secret mine, which they carried under the mount from within the city by conjecture, fetched away the earth again and were a long time undiscovered; so that still casting on, the mount grew still less, the earth being drawn away below and settling over the part where it was voided.

The Plataeans, nevertheless, fearing that they should not be able even thus to hold out, being few against many, devised this further. They gave over working at the high wall against the mount and, beginning at both ends of it where the wall was low, built another wall in form of a crescent, inward to the city; that if the great wall were taken, this might resist and put the enemy to make another mount, and by coming further in to be at double pains and withal more encompassable with shot.

The Peloponnesians, together with the rising of their mount, brought to the city their engines of battery. One of which, by the help of the mount, they applied to the high wall, wherewith they much shook it and put the Plataeans into great fear. And others to other parts of the wall, which the Plataeans partly turned aside by casting ropes about them and partly with great beams, which, being hung in long iron chains by either end upon two other great beams jetting over and inclining from above the wall like two horns, they drew up to them athwart; and where the engine was about to light, slacking the chains and letting their hands go, they let fall with violence to break the beak of it.