The shore cables, which united the ships together, and sustained the actual bridge or platform, were made of most carefully selected materials, and must have been of enormous strength; the ships were placed in close proximity one to another; and by the substitution of a double for a single line--of two bridges, in fact, for one--the solidity of the work was very largely augmented.

Yet, rare as was the skill shown, solid and compact as were the causeways thus thrown by human art over the sea, they were found inadequate to the end desired.

The great work of Xerxes, far the most elaborate of its class, failed to withstand the fury of the elements for a single year; the bridge, constructed in one autumn, was utterly swept away in the next; and the army which had crossed into Europe by its aid had to embark as it best could, and return on board ship to Asia.
As the furnishing of the Persian fleet was left wholly to the subject nations of the Empire, so was its manning intrusted to them almost entirely.

Phoenicians, Syrians, Egyptians, Cypriots, Cilicians, Lycians, Pamphylians, Carians, Greeks, equipped in the several costumes of their countries, served side by side in their respective contingents of ships, thereby giving the fleet nearly the same motley appearance which was presented by the army.

In one respect alone did the navy exhibit superior uniformity to their sister service--the _epibatae_, or "marines," who formed the whole fighting force of the fleet while it kept the sea, was a nearly homogeneous body, consisting of three races only (two of which were closely allied), namely, Persians, Medes, and Sacse.