History of the Peloponnesian War

The Syracusans plied their missiles on them from the docks, and the men on the ship of burden discharged theirs in return; and at last the Athenians removed the greater part of the piles. But the most dangerous part of the stockade was that out of sight:

for there were some of the piles which they drove that did not rise above the surface of the sea, so that it was dangerous to approach, lest any one, through not seeing them beforehand, might strike his ship on them, as on a sunken rock. But even in the case of these divers went down and sawed them off for a reward; but the Syracusans made, notwithstanding, a fresh stockade.

Many other also were the contrivances which they employed against one another, as was natural with the armaments lying near, and opposed to, each other; and they were engaged in skirmishes, and attempts of every kind.