History of the Peloponnesian War

But the Peloponnesians became aware of this, and threw into the breach clay packed in reedmats that it might not filter through like the loose earth and be carried away.

But the besieged, thwarted in this direction, gave up that plan and dug a mine from the town, and, guessing when they had got beneath the mound, once more began to draw away the earth to their side, this time from underneath; and for a long time they worked unnoticed by those outside, so that in spite of what they heaped on these made less progress, because their mound, as it was sapped from below, constantly kept settling down into the hollow space.

But fearing that even so they would not be able to hold out, few as they were against a multitude, they devised this further expedient: they stopped working on the high structure opposite the mound, and starting at the low part of the wall on either side of it they began building a crescent-shaped rampart on the inward or city side of it, in order that, if the high wall should be taken, this might offer resistance; the enemy would thus have to raise a second mound to oppose the new rampart, and as they advanced and came inside the crescent they would not only have their labour twice over, but would also be more exposed to attack on both sides.

But the Peloponnesians, while going on with their mound, also brought up engines against the city: one was moved forward over the mound, and shook down a great part of the high structure, terrifying the Plataeans, while others were brought to bear at different parts of the wall. But the Plataeans threw nooses over these and pulled them up. They also suspended great beams by long iron chains attached at either end to two poles which rested on the wall and extended over it; then they hauled up the beams at right angles[*](i.e. parallel to the wall) to the battering-ram and when it was about to strike anywhere let go the beam by allowing the chains to run slack and not keeping hold of them; whereupon the beam would fall with a rush and break off the head of the battering-ram.