ned the most important fortresses of
the empire, such as Sardes, Memphis, Elephantine, Daphnae, Babylon, and
many others, to hold the restless natives in check. These were, indeed,
the only regular troops on which the king could always rely. Whenever
a war broke out which demanded no special effort, the satraps of the
provinces directly involved summoned the military contingents of the
cities and vassal states under their control, and by concerted action
endeavoured to bring the affair to a successful issue without the
necessity of an appeal to the central authority. If, on the contrary,
troubles arose which threatened the welfare of the whole empire, and the
sovereign felt called upon to conduct the campaign in person, he would
mobilise his guard, and summon the reserves from several provinces or
even from all of them. Veritable hordes of recruits then poured in, but
these masses of troops, differing from each other in their equipment and
methods of fighting, in disposition and in language, formed a herd
of men rather than an army. They had no cohesion or confidence in
themselves, and their leaders, unaccustomed to command such enormous
numbers, suffered themselves to be led rather than exercise authority
as guides. Any good qualities the troops may have possessed were
neutralised by lack of unity in their methods of action, and their
actual faults exaggerated this defect, so that, in spite of their
splendid powers of endurance and their courage under every ordeal, they
ran the risk of finding themselves in a state of hopeless inferiority
when called upon to meet armies very much smaller, but composed of
homogenous elements, all animated with the same spirit and drilled in
the same school.

By continual conquests, the Persians were now reduced to only two
outlets for their energies, in two opposite directions--in the east
towards India, in the west towards Greece. Everywhere else their advance
was arrested by the sea or other obstacles almost as impassable to their
heavily armed battalions: to the north the empire was bounded by the
Black Sea, the Caucasus, the Caspian Sea, and the Siberian steppes; to
the south, by the Indian Ocean, the sandy table-land of Arabia, and the
African deserts. At one moment, about 512 B.C., it is possible that they
pushed forward towards the east.*

* India is not referred to in the Behistun Inscription, but
is mentioned in one of the Inscriptions of Persepolis, and
in tha