History of the Peloponnesian War

The same winter the Plataeans, (for they were still besieged by the Peloponnesians and Boeotians,) when distressed by the failure of their provisions, and when there was no hope of aid from Attica, and no other means of safety presented itself, both themselves and the Athenians who were besieged with them formed a design, in which they were at first unanimous, for all to sally forth and pass the walls of the enemy, if they could force their way over them; the attempt having been suggested to them by Theaenetus son of Tolmidas, a soothsayer, and Eupomidas son of Daïmachus, who was also one of their generals.

Subsequently half of them shrank from it, thinking it a great risk; but about two hundred and twenty voluntarily persevered in the attempt, [which they effected] in the following manner.

They made ladders to suit the height of the enemy's wall, measuring by the layers of bricks, where the wall looking toward them happened to be imperfectly whitewashed. Now many counted the layers at the same time; and though some would naturally miss the correct calculation, the majority would attain it; especially as they counted them many times over, and were also at no great distance, but the wall was easily observed by them as far as they wished.

In this way they ascertained the proper length of the ladders, guessing the measure from the thickness of the bricks.

Now the wall of the Peloponnesians was of the following construction. It consisted of two lines round the place, one against the Plataeans, and another in case any one should attack them on the outside from Athens; and the lines were about sixteen feet apart.

In this interval then of the sixteen feet there were quarters built, and partitioned out amongst the soldiers that were on guard; and these were continuous, so that it appeared but one thick wall, with battlements on each side.

At the distance of every ten battlements there were towers, of considerable size, and of the same breadth as the wall, reaching both to its inner and its outer front, so that there was no passage by the side of a tower, but they passed through the middle of them.

During the nights therefore, whenever it was stormy and wet weather, they used to leave the battlements, and to keep watch from the towers, as they were only at a short distance one from another, and were covered in above. Such then was the nature of the wall by which the Plataeans were enclosed.