were far superior to the ordinary irregular troops of
Greek warfare. They were about six thousand strong. Besides these, he
had several bodies of Greek regular infantry; and he had archers,
slingers, and javelin-men, who fought also with broadsword and target,
and who were principally supplied him by the highlanders of Illyria and
Thracia.

The main strength of his cavalry consisted in two chosen regiments of
cuirassiers, one Macedonian and one Thessalian, each of which was about
fifteen hundred strong. They were provided with long lances and heavy
swords, and horse as well as man was fully equipped with defensive
armor. Other regiments of regular cavalry were less heavily armed, and
there were several bodies of light-horsemen, whom Alexander's conquests
in Egypt and Syria had enabled him to mount superbly.

A little before the end of August, Alexander crossed the Euphrates at
Thapsacus, a small corps of Persian cavalry under Mazaeus retiring
before him. Alexander was too prudent to march down through the
Mesopotamian deserts, and continued to advance eastward with the
intention of passing the Tigris, and then, if he was unable to find
Darius and bring him to action, of marching southward on the left side
of that river along the skirts of a mountainous district where his men
would suffer less from heat and thirst, and where provisions would be
more abundant.

Darius, finding that his adversary was not to be enticed into the march
through Mesopotamia against his capital, determined to remain on the
battle-ground, which he had chosen on the left of the Tigris; where, if
his enemy met a defeat or a check, the destruction of the invaders would
be certain with two such rivers as the Euphrates and the Tigris in their
rear.

The Persian King availed himself to the utmost of every advantage in his
power. He caused a large space of ground to be carefully levelled for
the operation of his scythe-armed chariots; and he deposited his
military stores in the strong town of Arbela, about twenty miles in his
rear. The rhetoricians of after-ages have loved to describe Darius
Codomanus as a second Xerxes in ostentation and imbecility; but a fair
examination of his generalship in this his last campaign shows that he
was worthy of bearing the same name as his great predecessor, the royal
son of Hystaspes.

On learning that Darius was with a large army on the left of the Tigris,
Alexander hurried forward and crossed that river withou