They stationed at the prow of each vessel a flying bridge, which could be lowered in front or on either side; it was furnished on both sides with parapets, and had space for two men in front.

When the enemy's vessel was sailing up to strike the Roman one, or was lying alongside of it after the thrust had been evaded, the bridge on deck was suddenly lowered and fastened to its opponent by means of a grappling- iron: this not only prevented the running down, but enabled the Roman marines to pass along the bridge to the enemy's deck and to carry it by assault as in a conflict on land.

No distinct body of marines was formed, but land troops were employed, when required, for this maritime service.

In one instance as many as 120 legionaries fought in each ship on occasion of a great naval battle; in that case however the Roman fleet had at the same time a landing-army on board.
In this way the Romans created a fleet which was a match for the Carthaginians.

Those err, who represent this building of a Roman fleet as a fairy tale, and besides they miss their aim; the feat must be understood in order to be admired.