which we have any mention during the disastrous retreat of his army are the Saracenic allies of Sapor.  In these auxiliaries, and in the Cadusians from the Caspian region, the Persians had always, when they wished it, a cavalry excellently suited for light service; but their own horse during the Sassanian period seems to have been entirely of the heavy kind, armed and equipped, that is, very much as Chosroes II. is seen to bo at Takht-i-Bostan.  The horses themselves wore heavily armored about their head, neck, and chest; the rider wore a coat of mail which completely covered his body as far as the hips, and a strong helmet, with a vizor, which left no part of the face exposed but the eyes.  He carried a small round shield on his left arm, and had for weapons a heavy spear, a sword, and a bow and arrows.  He did not fear a collision with the best Roman troops.  The Sassanian horse often charged the infantry of the legions with success, and drove it headlong from the field of battle.  In time of peace, the royal guards were more simply accoutred. [See PLATE XLVI.]

The archers formed the elite of the Persian infantry.  They were trained to deliver their arrows with extreme rapidity, and with an aim that was almost unerring.  The huge wattled shields, adopted by the Achaemenian Persians from the Assyrians, still remained in use; and from behind a row of these, rested upon the ground and forming a sort of loop-holed wall, the Sassanian bowmen shot their weapons with great effect; nor was it until their store of arrows was exhausted that the Romans, ordinarily, felt themselves upon even terms with their enemy.  Sometimes the archers, instead of thus fighting in line, were intermixed with the heavy horse, with which it was not difficult for them to keep pace.  They galled the foe with their constant discharges from between the ranks of the horsemen, remaining themselves in comparative security, as the legions rarely ventured to charge the Persian mailed cavalry.  If they were forced to retreat, they still shot backwards as they fled; and it was a proverbial saying with the Romans that they were then especially formidable.

The ordinary footmen seem to have been armed with swords and spears, perhaps also with darts.  They were generally stationed behind the archers, who, however, retired through their ranks when close fighting began.  They had little defensive armor; but still seem to have fought with spirit and tenacity, being a fair match for the legionaries under ordinary circumstances, and superior to most other adversaries.

It is uncertain how the various arms of the service were organized internally.  We do not hear of any divisions corresponding to the Roman legions or to modern regiments; yet it is difficult to suppose that there were not some such bodies.  Perhaps each satrap of a province commanded the troops raised within his government, taking the actual lead of the cavalry or the infantry at his discretion.  The Crown doubtless appointed the commanders-in-chief—­the Sparapets, Spaha-pets, or Sipehbeds, as well as the other generals (arzbeds), the head of the commissariat (hambarapet or hambarahapet), and the commander of the elephants (zendkapet).  The satraps may have acted as colonels of regiments under the arzbeds, and may probably have had the nomination of the subordinate (regimental) officers.