According to the pioneering historian Herodotus, "They joined together triremes and penteconters
, 360 to support the bridge on the side of the Euxine Sea, and 314 to sustain the other; and these they placed at right angles to the sea, and in the direction of the current of the Hellespont, relieving by these means the tension of the shore cables." When the work was done, Herodotus reports, the engineers secured the bridges, making "cables taut from the shore by the help of wooden capstans." When the bridge was stable, a vast forest of trees was sawn into planks and used to serve as the basis for a roadbed.
Philip was in a position to 'practise piracy', because he had developed a fleet of triaconters and penteconters, which were fast under oar and could attack the small merchantmen of the time.(13) Athens and Philip being at war raided each other's shipping in the northern Aegean.
Moreover, he enjoyed in that area the alliance of Perinthus and Byzantium, was negotiating with Chios, Rhodes and their allies (FGrH 115 [Theopompus] F 164), and had himself built penteconters and triaconters which were ideal for raiding merchant-ships, or as the Athenians put it for 'piracy' (Just.