The utility of such a work is evident.  Without it Xerxes must have been reduced to the necessity of embarking in ships, conveying across the strait, and disembarking, not only his entire host, but all its stores, tents, baggage, horses, camels, and sumpter-beasts.  If the numbers of his army approached even the lowest estimate that has been formed of them, it is not too much to say that many weeks must have been spent in this operation.  As it was, the whole expedition marched across in seven days.  In the case of ship conveyance, continual accidents would have happened:  the transport would from time to time have been interrupted by bad weather; and great catastrophes might have occurred.  By means of the bridge the passage was probably effected without any loss of either man or beast.  Moreover, the bridge once established, there was a safe line of communication thenceforth between the army in Europe and the headquarters of the Persian power in Asia, along which might pass couriers, supplies, and reinforcements, if they should be needed.  Further, the grandeur, massiveness, and apparent stability of the work was calculated to impose upon the minds of men, and to diminish their power of resistance by impressing them strongly with a sense of the irresistible greatness and strength of the invader.

The canal of Athos was also quite a legitimate and judicious undertaking. [PLATE LXI.] No portion of the Greek coast is so dangerous as that about Athos.  Greek boatmen even at the present day refuse to attempt the circumnavigation; and probably any government less apathetic than that of the Turks would at once re-open the old cutting.  The work was one of very little difficulty, the breadth of the isthmus being less than a mile and a half, the material sand and marl, and the greatest height of the natural ground above the level of the sea about fifty feet.  The construction of a canal in such a locality was certainly better than the formation of a ship-groove or Diolcus—­the substitute for it proposed by Ferodotus, [PLATE LXI.] not to mention that it is doubtful whether at the time that this cutting was made ship-grooves were known even to the Greeks.

[Illustration:  PLATE LXI.]

Xerxes, having brought his preparations into a state of forwardness, having completed his canal and his bridge—­after one failure with the latter, for which the constructors and the sea were punished—­proceeded, in the year B.C. 481, along the “Royal Road” from Susa to Sardis, and wintered at the Lydian capital.  His army is said to have accompanied him; but more probably it joined him in the spring, flocking in, contingent after contingent, from the various provinces of his vast Empire.  Forty-nine nations, according to Herodotus, served under his standard; and their contingents made up a grand total of eighteen hundred thousand men.  Of these, eighty thousand were cavalry, while twenty thousand rode in chariots or on camels; the remainder served on foot.  There are no sufficient