According to another account, Rustam sent the Arab embassy to King Yazdegard, who broke off the interview in anger and rebuked Rustam for referring the envoys to the court. But those historians who assume from Rustam’s “contemptuous denunciations” of the Arab envoys that he was a man of “overweening pride,” are surely mistaken. For exhibitions of resentment is sometimes only an aspect of diplomacy. Moreover, we cannot rely on all the details of these interviews as given to us. As one authority has observed in the accounts of these wars and related transactions, "much is drawn evidently from the imaginations of the traditions". As the great Noldeke says “we must accept with great caution the sayings of Arab warriors based on confused recollections”. For, in fact, the events, the circumstances and the recollections were all confused.
The negotiations were followed by three “days of grace”, granted to the Persians to consider the terms offered by the Arab general. It is not too much to say that this delay of three days was fatal to the Persian cause, since it enabled the Syrian reinforcements commanded by that redoubtable warrior al-Qa'qa to arrive at the critical juncture of the battle. It was he, indeed who was the foremost champion on the Arab side, since Sa'd himself was unable to mount his horse to lead the fight on account of his illness.
At the end of that time, Rustam invited the Arab commander to cross the river and begin the battle. But the latter was too prudent to abandon his strong and well-covered position. He left it to Rustam to cross the river in the face of strong opposition and to seek an engagement with such a great obstacle at his back. The Arabs stoutly defended the bridge of boats on the river; but the Persian engineers managed to throw a dam across the stream and their army crossed over, with Rustam encouraging his men by observing "by tomorrow we shall have beaten them small". Whatever despondency he might have felt at heart, it was his duty to hearten his troops, and he performed it well.
As regards the dispositions for the battle, our information is scanty and vague. But we know that the wings of the Persian army were commanded by the generals Hurmuzan (Satrap of Pars) and Mihran Bahram Razi, while Jalenus led the advance guard. Pirozan was placed in command of the rear-guard. Rustam had at his disposal 30 (or by other accounts 33) elephants. Of these, 18 were placed in the center and the rest on the wings. Rustam had a sort of throne made for himself from which he could direct the operations. Prof. Christensen tells us that this was the constant practice in battles royal of the Sassanide dynasty. What was unique in this case was that the Persian prince kept in constant communication with the court at Ctesiphon by an uninterrupted chain of men stationed at suitable intervals, who could communicate the news of the events of the battle to King Yazdegard. It was a human "telephone" that Rustam had thus installed.
All accounts agree that the first day of the battle was one of entire success for the Persians, and that at the end of it, the Arabs and their leaders were in a state of profound despondency. After the usual series of single combats, the line of elephants advanced upon the Arab army and bore down all before them. In vain, the bravest of Arab warriors performed deeds of valour like those of Abu Mihjan. The elephants were not to be denied. At last the Arab commander-in-chief appealed to the gallant Asim of the Tamim tribe to stop the advance of elephants "at all costs". Asim advanced with his archers against the elephants, shot down some of the soldiers riding the elephants and cut the girths of their "howdahs". As the "howdahs" fell to the ground the riders were massacred. But though the advance of the elephants was thus stayed, the battle lasted without interruption until sunset. No wonder that as Sir W. Muir says “the Arab force was downcast.”
Ya'qubi, in his account of the first day's battle, throws additional light on the maneuvers of prince Rustam. According to him, that general attempted to surprise the Arab commander in the castle of al-'Udzayb, whence he was surveying the fight. But the Arabs rallied to the defense of their general successfully and checked the attempt.
The second day of the battle, however, opened well for the Arabs, since it brought reinforcements for them from Syria. The advance guard of these succors was led by al-Qa'qa; and it would not be too much to say (that to him the Arabs owed the victory of Qadisiyyah. His arrival gave great confidence to his side, especially as he signaled his arrival by a sudden attack on the leading Persian file, where he fought Bahman Hajib; the victor of the battle of the Bridge.
Al-Qa’qa with two other Arab warriors rushed against Bahman shouting that he wanted to avenge Abu 'Ubaid and others who had perished in that battle. Bahman too received help from two Persian champions, Pirozan and Bindawan. But Al-Qa'qa struck down Pirozan while his companions smote the other two Persians.
The Persians were further dismayed as other parties of reinforcements came up in batches. “The spirits of the Arabs rose”, observes Sir W. Muir, “and they forgot the disasters of yesterday.” Above all, the Persians were fighting without their former advantage, since the harness of their elephant corps was being repaired, that equipment having been cut in the first day of the battle, while with an improvised camel corps, the Arabs drove back the Persian cavalry. But then Rustam descended from his post of observation and restored the battle with the help of his well disciplined infantry. Thus closed “the day of Aghwath”, in which the Arabs lost over 2,000 men; and, owing to such heavy mortality, Sa'd dispensed with the ceremony of washing the bodies of the dead before lowering them into hastily constructed tombs.
On the third day of the battle (called Yaum. Ghimas or Imas) the event still remained doubtful. But the arrival of Hisham with 700 more men from Syria heartened the Arab troops, especially since by strategy these reinforcements advanced at intervals in batches of 100 men; and thus the succors were magnified. Meanwhile the harness of the elephants had been repaired and they again advanced to the attack, But, acting on the advice of some Persian refugees, al-Qa'qa, his brother Asim and others advanced against these pachyderms and wounded them in their trunks and eyes. Thus assailed, the elephants wavered for a time between the two armies; but, later on, they charged through the Persian army and stampeded across the canal. Rustam, however, succeeded in maintaining the day. No wonder that, in the opinion of the great authority on the battle, on Sayf b. Umar the Arabs would have been defeated on that day but for the skill of al-Qa’qa and the arrival of reinforcements under Hisham. We have also to remember when appraising the services of al-Qa'qa to the Arab cause that he organized a sort of camel corps in order to neutralize the advance of the Persian cavalry; for the horses of the Persians were unaccustomed to the sight, sound, and the smell of the camels. The result of this ruse of al-Qa'qa was a stampede of the Persian cavalry into the lines of the infantry which caused serious trouble.
A confused struggle raged throughout the third night of the battle, which has been made famous in history under the designation of the “Laylah al-Harir”. According to Caetani, the title alluded to the groans of pain heard throughout its course; while Wellhausen supposes that the word "harir " means suppressed cries of combating animals; for the two sides were now too exhausted and furious to pronounce coherent challenges. It is curious, adds Caetani, that in the struggle at Yermuk, too, there was a night so named. On the Arab side, there were some moves attempted in the course of this night, though only partially under the direction of the High Command. Thus Sa'd ordered Tulayhah bin Khuwaylid to guard the fords of the canal below the Arab position, lest the Persians might be attempting a flanking movement. But Tulayhali could not resist the temptation to cross the canal, and boldly carried out his design. He was, however, driven back by the Persians across the canal. Other Arab bands followed up this move and attacked the Persians shouting their own tribal names to give some information to their leader of what was going on. Sa'd had to pardon such acts of "brave indiscipline". Like the Arabs; the Persians kept up shouting by tribes or regiments during the second and third nights to keep up their confidence. Needless to add that these night operations were in no sense directed by the generals on either side. They marked the exhaustion as well as the exacerbation on either side, and an effort to bring the battle to a speedy termination.
It was only on the morning of the fourth day (Sunday) of the battle that the Persian army gave way. One important factor in this was a terrific dust storm which, as Sayf bin 'Umar has recorded, beat down even the pavilion under which Rustam was watching and directing the operations. Weil has justly observed that "as in Palestine the south wind forced the Christians to fly before the followers of Islam, so at Qadisiyyah such clouds of dust were blown against the Magians by a west wind, so heavy that even the pursuing Mohammedans could not see the faces of their foes.
Another factor in the Persian defeat was a last desperate charge advised by Qa'qa. As all tents had been thrown down, Rustam who had been directing operations in the center was compelled to take refuge under a mule laden with bags of treasure; but one of the heavy bags of treasure fell on him and crushed his back. Rendered thus incapacitated and incapable of defending himself, Rustam threw himself into the canal in order to cross it and was slain there. There are many accounts of his death. and many claimants to the honor of terminating such a great career. The usual account is that he was slain by Hillal bin ‘Ullafah. According to Bala-dhuri however "Rustam was slain and his body was found covered with so many blows and stabs that the one who gave the fatal blow could not be determined.
Amir-bin-Madikarib, Tulayhah ibn-Khuwaylid, Kurt ibn Jammah and Dirar ibnal-Azwar had all rushed at him. Some say that Rustam was killed by Zuhair ibn-'Abd Shams; others by 'Auwam ibn-'Abd Shams. In still another version, we read that Rustam shot an arrow at Hillal who was riding towards him and transfixed his foot to his stirrup. Upon this, Hillal rushed against Rustam and dispatched him. However that may be, with the death of Rustam the Persian army was in full flight.
On Rustam's death, no one was left to lead the army back and hence, according to Tabari, it lost 10,000 men in its flight besides those that had been killed in the three earlier days. The army corps led by Pirozan and Hormuzan were lucky in being the first to re-cross the dam at the canal al-Atiq; but before Jalenus could follow with his corps, the dam was swept away and that general was slain while trying to rally his men. Amongst other noted fugitives were Zadz Buhaysh and Qarin, who came of a family that had given many a noted warrior to old Iran.
It is noteworthy that the Arab chronologist, Sayf bin 'Umar, to whom we owe so many traditions of the great battle, has been at pains to preserve the names of some brave Persian chiefs, who with their followers refused to retreat. They preferred after the retreat to "die gloriously". On this role of honor Sayf, and following him Tabari, places the names of Sharyar Kanara, Hirbidz, Farrukhan Ahwazi and Khusrawshnum Hamdani. As Waqidi also observes, "a group of Persians planting their banner firmly in the ground said ‘we shall not leave our position until we die'." But although such rallies were highly honorable to those who took a part in them, they cost Persia the lives of generals who could be ill spared. The same might be said of the struggle of Nakhveraghan at Dayr-I-Ka’b. Thereafter, no generals were left who could direct the defense of Ctesiphon.
Incidentally it might be observed that in the mention of the brave Hirbidz we have the only authority for the fact that men of the priestly caste served as fighting officers during the Sassanian age.
Neither as a tactician, nor as a strategist, could Rustam be said justly to have been found wanting, and historians have not laid at his door the adverse result of the great battle. As regards tactics, he could not be blamed for the stampede of elephants, which was certainly a great misfortune for the Persian cause; and he must be praised for restoring the battle after that event. It was in fact the advent of great reinforcements from Syria that decided the battle. Perhaps, Rustam had some inkling of the imminent advent of these fresh hostile forces; and it was that knowledge, and no "overweening confidence", that impelled him to cross the canal al-Atiq and to bring on a battle with the well-chosen and strong Arab position before him and the canal in his rear. For the Iranian general was no rash assailant; and, as Caetani observes, Rustam knew the weakness of the Persian Empire at the time. Had he been able to prevail by a show of force, he would have been glad to return to Ctesiphon with the laurels of a great moral victory. His long delay before the battle showed that he was aware of Sa'd’s strategy of drawing the Persian army into the desert-a region well known to Arabs and adapted to their manoeuvres of cavalry but which would have been very unfavorable to the Persians. Rustam's hands were also forced by Arab raids on the one hand and by his king's injunctions on the other.
It is all to Rustam’s credit that he faced the Arab invaders in the hardest fought battle that they encountered either before or after. In none of the battles that these invaders had fought in Syria with the forces of Heraclius had they ever been brought so near defeat. It was no disgrace to prince Rustam that he fell after a gallant struggle against a unique combination of circumstances- the full tide of a Semitic national flood, the genius and policy of Caliph 'Umar, the desperate bravery of warriors like al-Qa’qa, Hashim and Tulayha, and finally the rage of nature itself as shown in the furious dust storm, which went far to decide the result of the well-fought field of al-Qadisiyyah. It is also worth noting what a mass of traditions -in fact, a veritable epic, has been constructed by the Arabs about the Qadisiyyah. In particular, the Iraqi school of traditionalists has labored hard to embellish and ornament the epic of this fight, while there is also a Medinah version which is less labored & ornamented. Finally, in times to come, the fight of Qadisiyyah served as a standard and a pattern to the Arabs of what a really hard-fought field was like. Thus, when the great battle of Siffin, with all the ferocious intensity of a civil conflict, had to be described, it was compared to that of Qadisiyyah.
The importance, which both friends and foes attached to the power and personality of Rustam, was well illustrated soon after his death. Thus, four thousand cavaliers from Day-lam, who had formed the "royal regiment" under Rustam, did not hesitate to cast in their lot at once with the Arabs when he had passed away, feeling that there was now no future with Persia. Simultaneously, Christians belonging to the Bedouin tribes on both sides of the Euphrates came to the Arab general and said: "Now that Rustam has been slain, we will accept the new religion." Obviously, friend as well as foe, regarded the death of Rustam as equivalent to the complete triumph of the Arabs and the passing away of the Persian power; they felt that as long as he lived, the prospects of the invaders were doubtful indeed, but that with his death the doom of Persia was sealed.
What better epitaph can a patriotic general either desire or require?