Next, an excuse for marching up-country, at the head of all these forces, was found in the need of suppressing the Pisidians.  He advanced from Sardis into Phrygia, where his musters were completed at Celaenae.  A review was held at Tyriaeum, where the Cilician queen, who had supplied funds, was badly frightened by a mock charge of the Greek contingent.  When the advance had reached Tarsus, there was almost a mutiny among the Greeks, who were suspicious of the intentions of Cyrus.  The diplomacy, however, of their principal general, Clearchus, the Lacedaemonian, coupled with promises of increased pay, prevailed, though it had long been obvious that Pisidia was not the objective of the expedition.

Further reinforcements were received at Issus, the eastern seaport of Cilicia; Cyrus then marched through the Cilician gate into Syria.  At Myriandrus two Greek commanders, probably through jealousy of Clearchus, deserted.  Cyrus won popularity by refusing to presume thereon; and the whole force now struck inland to Thapsacus, on the Euphrates.

At Thapsacus, Cyrus announced his purpose.  The Greek soldiers were angry with their generals for having, as they supposed, wilfully misled them, but were mollified by promise of large rewards.  One of the commanders, Menon, won the approval of Cyrus by being the first to lead his own contingent across the Euphrates on his own initiative.  The advance was now conducted by forced marches through a painfully sterile country.  In the course of this, the troops of Clearchus and Menon very nearly came to blows; the intervention of Proxenus only made matters worse; and order was restored by the arrival of Cyrus, who pointed out that the whole expedition must be ruined if the Greeks fell out among themselves.

By this time, Artaxerxes had realised that the repeated warnings of Tissaphernes and others were justified; and as the expedition neared Babylonia, signs of the enemy became apparent in the deliberate devastation of the country.  Here Orontes, one of the principal Persian officers of Cyrus, was convicted of treason and put to death.

The army was again reviewed, the whole force amounting to some 100,000 barbarians and nearly 14,000 Greeks; the enemy were reputed to number over 1,000,000, though not so many took part in the engagement.  Cyrus now advanced, expecting battle immediately at an entrenched pass; but, finding this unoccupied, he did not maintain battle order; which was hurriedly taken up on news of the approach of the royal forces.  The Greeks, under Clearchus, occupied the right wing, Cyrus being in the centre, and Ariaeus on the left.  The king’s army was so large that its centre extended beyond the left of Cyrus.

The Greeks advanced on the royalist left, which broke and fled almost without a blow.  Thinking that the Greeks might be intercepted and cut off, Cyrus charged the centre in person with his bodyguard, and routed the opposing troops; but dashing forward in the hope of capturing Artaxerxes, was himself pierced by a javelin, and fell dead on the field.  So ended the career of the most brilliant Persian since Cyrus the Great had established the Persian Empire; brave, accomplished, the mirror of honour, just himself and the rewarder of justice in others, generous and most loyal to his friends.