Battle of al-Qadisiyyah

Battle of al-Qādisiyyah
Part of the Muslim conquest of Sassanid empire
Date 16–19 November 636 Location Al-Qādisiyyah, Iraq Result Decisive Rashidun victory Territorial changes Muslim Rashiduns annex Sassanid Empire
Belligerents
Sasanid empire	Rashidun Caliphate
Commanders and leaders
Rostam Farrokhzād  † Bahman Jadhuyih  † Hormuzan Jalinus  † Shahriyar bin Kanara † Mihran Razi Piruz Khosrow Kanadbak Grigor II Novirak  † Tiruyih Mushegh III  † Javanshir Nakhiragan	Sa`d ibn Abī Waqqās Al-Muthanna ibn Haritha Al-Qa'qa'a ibn Amr at-Tamimi Asim ibn Amr Abdullah ibn Al-Mutim Shurhabeel ibn As samt Zuhra ibn al-Hawiyya Jarreer bin Abdullah Al-Bijli Tulayha
Strength
200,000 80,000-200,000 33 War Elephants (medieval estimates)	30,000-40,000
Casualties and losses
40,000	8,500

The Battle of al-Qādisiyyah (Template:Lang-ar; transliteration, Ma'rakatu al-Qādisiyyah; alternative spellings: Qadisiyya, Qadisiyyah, Kadisiya, Ghadesiyeh), fought in 636, is said to be a decisive engagement between the Arab Muslim army and the Sassanid Persian army during the first period of Muslim expansion. It resulted in the Islamic conquest of Persia and was key to the conquest of Iraq. The battle also saw the alleged alliance of Emperor Yazdegerd III with Byzantine Emperor Heraclius, who married his granddaughter Manyanh to Yazdegerd as a symbol of alliance.

Background

Main article: Fall of the Sasanian Empire

During the lifetime of Islamic prophet, Muhammad, Persia was ruled by Emperor Khosrau II, who waged a war against the Byzantine Empire to avenge the murder of Emperor Maurice. The Sassanid army invaded and captured Syria, Egypt, and Anatolia, and the True Cross was carried away in triumph. Emperor Heraclius succeeded Phocas in 610 and led the Byzantines in a war of reconquest, successfully regaining territory lost to the Sassanid Empire. He defeated a small Persian army at the final Battle of Nineveh and advanced towards Ctesiphon. After a successful coup by one of Khosrau's sons Kavadh II—Kavadh then ordered the execution of his father along with all his brothers and half-brothers, which included Mardanshah, the favorite son of Khosrau II, who was heir to the Sasanian throne. His next move was to make peace with the Romans and return all captured territories. At the same time Turks had attacked the North of Persia with a massive army. Heraclius ordered his armies to retreat after a pact was signed with the newly appointed Persian Emperor Kavadh II. According to the pact, the True Cross would be given back to Heraclius, and all Byzantine territory that the Persians had captured would be evacuated.

Internal conflicts of succession

Khosrau II was murdered in his palace by his son Kavadh II in 628. Kavadh II put his 18 brothers to death and began negotiations with Heraclius, but he died suddenly after a reign of only few months after getting infected by plague. Thus began a civil war. Ardashir III (c. 621–630), son of Kavadh II, was raised to the throne at age seven but was killed 18 months later by his general Farrokhan, who was called Shahrbaraz, a title meaning "the Boar of the Empire". Shahrbaraz had taken Damascus and Jerusalem from the Byzantine Empire in 613 and 614 respectively. Following the Persian surrender in 628, Shahrbaraz was heavily involved in the intrigues of the Sassanian court.

In 629, he failed to deal with the invasion of Armenia by a Khazar-Gokturk force under Chorpan Tarkhan. On 9 June 629 Shahrbaraz was slain and succeeded by Purandokht, the daughter of Khosrau II. She was the 26th sovereign Monarch of Persia, ruling from the 17 June 629 to 16 June 630, and was one of only two women to sit on the Sassanid throne, the other being her sister Azarmidokht. She was made Queen of Persia on the understanding that she would vacate the throne upon Yazdgerd III attaining majority. She attempted to bring stability to the empire by the implementation of justice, reconstruction of the infrastructure, lowering taxes, minting coins, and a peace treaty with the Byzantine Empire. She also appointed Rostam Farrokhzād as the commander-in-chief of the Persian army. She was largely unsuccessful in restoring the power of the central authority, however, which was weakened considerably by civil wars, and she resigned or was murdered soon after. She was replaced by her sister Azarmidokht, who in turn was replaced by Hormizd VI, a noble of the Persian court.

After five years of internal power struggle, Yazdegerd III (the grandson of Khosrau II) became emperor at the age of 8. However, the real pillars of the state were generals Rostam Farrokhzād and Piruz Khosrow (also known as Piruzan). There was violent friction between these two, although pressure from the Persian courtiers pushed this backstage. The coronation of Yazdegerd III infused new life into the Sassanid Empire.

Rise of The Caliphate and invasion of Iraq

Main article: Islamic conquest of Mesopotamia

After the death of Muhammad, Abu Bakr established control over Arabia through the Ridda Wars and then launched campaigns against the remaining Arabs of Syria and Palestine. He triggered the trajectory that would in few decades form the largest empire the world had ever seen. He thus put the nascent Islamic empire on a collision course with the Byzantine and Sassanid empires, which had been disputing these territories for centuries. The wars soon became a matter of conquest that would eventually result in the demise of the Sassanid empire, and the annexation of all the Byzantine Empire's southern and eastern territory. To make certain of victory, Abu Bakr decided that the invading army would consist entirely of volunteers and would be commanded by his best general, Khalid ibn al-Walid. Khalid won quick victories in four consecutive battles: the Battle of Chains, fought in April 633; the Battle of River, fought in the third week of April 633; the Battle of Walaja, fought in May 633; followed by the decisive Battle of Ullais, fought in mid-May, 633. By now the Persian Empire was struggling, and in the last week of May 633, the capital city of Iraq, Al-Hirah, fell to the Muslims after the Battle of Hira. Thereafter, the Siege of Al-Anbar during June–July 633 resulted in surrender of the city after strong resistance. Khalid then moved towards the south and conquered the city of Ein ul Tamr after the Battle of Ein-ul-Tamr in the last week of July, 633. In November 633, the Persian counter-attack was repulsed by Khalid. In December 633, Muslim forces reached the border city of Firaz, where Khalid defeated the combined Sassanid, Byzantine, and Christian Arab armies in the Battle of Firaz. This was the last battle in the conquest of Iraq.

Map detailing the route of Khalid ibn Walid's conquest of Iraq

By this time, with the exception of Ctesiphon, Khalid had captured all of Iraq. However, circumstances changed on the western front. The Byzantine army soon came in direct conflict in Syria and Palestine, and Khalid was sent with half of his army to deal with this new development. Soon after, Caliph Abu Bakr died in August 634 and was succeeded by Caliph Umar ibn al-Khattāb. Muslim forces in Iraq were too few to control the region. After the devastating invasion by Khalid, Persians took time to recover; political instability was at its peak at Ctesiphon. Once the Persians recovered, they concentrated more troops and mounted a counterattack. Muthanna ibn Harith, who was now commander-in-chief of the Muslim forces in Iraq, pulled his troops back from all outposts and evacuated Al-Hirah. He then retreated to the region near the Arabian Desert. Meanwhile, Umar sent reinforcements from Madinah under the command of Abu Ubaid. The reinforcements reached Iraq in October 634, and Abu Ubaid assumed the command of the army and defeated the Sassanids at the Battle of Namaraq near modern-day Kufa. Then, in the Battle of Kaskar, he recaptured Hira.

The Persians launched another counterattack and defeated the Muslims at Battle of the Bridge, which killed Abu Ubaid, and the Muslims suffered heavy losses. Muthanna then assumed command of the army and withdrew the remnant of his forces, about 3000 strong, across the Euphrates. The Persian commander Bahman (also known as Dhu al-Hajib) was committed to driving the Muslims away from Persian soil but was restrained from pursuing the defeated Muslims after being called back by Rustum to Ctesiphon to help in putting down the revolt against him. Muthanna retreated near the frontier of Arabia and called for reinforcements. After getting sufficient reinforcements, he re-entered the fray and camped at the western bank of Euphrates, where a Persian force intercepted him and was defeated.

Persian counter-attack

After Khalid left Iraq for Syria, Suwad, the fertile area between the Euphrates and the Tigris, remained unstable. Sometimes it was occupied by the Persians and sometimes by the Muslims. This "tit-for-tat" struggle continued until emperor Yazdgerd III consolidated his power and sought alliance with Heraclius in 635 in an effort to prepare for a massive counterattack. Heraclius married his daughter to Yazdegerd III, in accordance with Roman tradition to seal an alliance. Heraclius then prepared for a major offensive in the Levant. Meanwhile, Yazdegerd ordered a concentration of massive armies to reclaim Iraq for good. This was supposed to be a well-coordinated attack by both emperors to annihilate the power of their common enemy, Caliph Umar.

When Heraclius launched his offensive in May 636, Yazdegerd could not coordinate, so the plan was not carried out. Umar, allegedly having intelligence of this alliance, devised his own plan. He wanted to finish off business with the Byzantines first and then to reinforce the Muslim army at Yarmouk. He sent 6000 soldiers in small bands to give the impression of a continuous stream of reinforcements. Meanwhile, Umar engaged Yazdegerd III, ordering Saad ibn Abi Waqqas to enter in peace negotiations with him by inviting him to convert to Islam. Heraclius had instructed his general Vahan not to engage in battle with Muslims until his orders. However, fearing more reinforcement for the Muslims from Madinah and their growing strength, the Byzantines felt compelled to attack the Muslim forces before they got stronger. Heraclius's imperial army was annihilated at Battle of Yarmouk in August 636, three months before Qadisiyyah, ending the Roman Emperor's offensive. Nevertheless, Yazdegerd continued to execute his ambitious plan of attack and concentrated armies near his capital Ctesiphon. A large force was put under the control of veteran general Rostam and was cantoned at Valashabad near Ctesiphon. Receiving news of the preparations of this massive counter-attack, Umar ordered Muthana to retreat to the edge of Arabian Desert and abandon Iraq. The campaign of Iraq was now to be started again from the beginning.

Muslim battle preparation

Caliph Umar raised new armies from all over Arabia to send a large enough force to re-invade Iraq. Umar appointed Sa`d ibn Abī Waqqās, an important member of the Quraysh tribe as commander of this army. In May 636, Saad marched from his camp at Sisra (near Madinah) with an army of 4,000 men and was instructed to join other armies, concentrated in northern Arabia, on his way to Iraq. Saad, being less experienced in the matter of war, was instructed by Caliph Umar to seek the advice of the experienced commanders. Once Saad entered Iraq, Umar sent orders to him to halt at al-Qadisiyyah, a small town 30 miles from Kufah. Muslims marched to Qadisiyyah and camped there on July 636.

Umar continued to issue strategic orders and commands to his army throughout the campaign. He wanted victory on the Persian front, but he ran short of manpower and decided to lift the ban on the ex-apostate tribes of Arabia from participating in state affairs. As a result, the army raised was not professional but was instead composed of newly recruited contingents from all over Arabia. Umar was therefore more concerned about providing it with strategic aid. Umar was quite satisfied with developments on Byzantine front, however, as the veteran army there was commanded by Abu Ubaidah ibn al-Jarrah and Khalid ibn Walid, a military genius. After they won a decisive victory against the Byzantine army at the Yarmouk, Umar sent orders to Abu Ubaidah to immediately send a contingent of veterans to Iraq. Later, a force of 5,000 veterans of Yarmouk were also sent and arrived on the second day of the battle. This proved to be the turning point. The battle was fought predominantly between Umar and Rostam, rather than between Saad and Rostam. On the other hand, the bulk of the Sassanid army was also made up of new recruits since the bulk of regular Sassanid forces was destroyed during the Battle of Walaja and the Ullais.

Battlefield

The site of the Battle of Qadisiyyah, showing Muslim army (in red) and Sassanid army (in blue)

Qadisiyya was a small town on the west bank of the river Ateeq, a branch of the Euphrates. Al-Hira, ancient capital of Lakhmid Dynasty, was about thirty miles west. According to present day geography, it is situated at southwest of al-Hillah and Kufah in Iraq.

Troop deployment

Modern estimates suggest that the size of Sassanid forces was about 50,000-100,000 strong and Muslims around 30,000 strong after being reinforced by the Syrian contingent on second day of the battle. These figures come from studying the logistical capabilities of the combatants, the sustainability of their respective bases of operations, and the overall manpower constraints affecting the Sassanids and Arabs. Most scholars, however, agree that the Sassanid army and their allies outnumbered the Muslim Arabs by a sizable margin.

Sassanid Persia

The Persian army reached Qadisiyyah in July 636 and established their highly fortified camps on the eastern bank of the Ateeq river. There was a strong bridge over the Ateeq river, the only crossing to the main Sassanid camps, although they had boats available in reserve to cross the river.

The Sassanid Persian army, about 60,000 strong, fell into three main categories, infantry, heavy cavalry, and the Elephant corps. The Elephant corps was also known as the Indian corps, for the elephants were trained and brought from Persian provinces in India. On 16 November 636, the Sassanid army crossed over the west bank of Ateeq, and Rostam deployed his 45,000 infantry in four divisions, each about 150 meters apart from the other. 15,000 cavalry were divided among four divisions to be used as reserve for counter-attack and offensives. At Qadisiyyah, about 33 elephants were present, eight with each of the four divisions of army. The battle front was about 4 km long. The Sassanid Persians' right wing was commanded by Hormuzan, the right center by Jalinus, the rear guard by Piruzan, and the left wing by Mihran. Rostam himself was stationed at an elevated seat, shaded by a canopy, near the west bank of the river and behind the right center, where he enjoyed a wide view of the battlefield. By his side waved the Derafsh-e-Kāveyān (in Persian: درفش کاویان, the 'flag of Kāveh'), the standard of the Sassanid Persians. Rostam placed men at certain intervals between the battlefield and the Sassanid capital, Ctesiphon, to convey intelligence.

Rashidun

In July 636, the main Muslim army marched from Sharaf to Qadisiyya. After establishing camp, organizing the defenses, and securing the river heads, Saad sent parties inside the Suwad to conduct raids. Saad was continuously in contact with Caliph Umar, to whom he sent a detailed report of the geographical features of the land where the Muslims encamped and the land between Qaddasiyyah, Madinah, and the region where the Persians were concentrating their forces. The Muslim army at this point was about 30,000 strong, including 7,000 cavalry. Its strength rose to 36,000 strong once it was reinforced by the contingent from Syria and local Arabs allies. Saad was suffering from sciatica, and there were boils all over his body. He took a seat in the old royal palace at Qaddasiyyah from where he would direct the war operations and could have a good view of the battlefield. He appointed Khalid ibn Arfatah as his Deputy, who would carried out his instructions to the battlefield. The Rashidun infantry was deployed in four corps, each with its own cavalry regiment stationed at the rear for counter-attacks. Each corps was positioned about 150 meters from the other. The army was formed on a tribal and clan basis, so that every man would fight next to well-known comrades and so that tribes may be held accountable for any weakness.

Weaponry

The Muslim forces wore gilded helmets similar to the silver helmets of the Sassanid soldiers. Mail was commonly used to protect the face, neck, and cheeks, either as an aventail from the helmet or as a mail coif. Heavy leather sandals as well as Roman type sandal boots were also typical of the early Muslim soldiers. Armor included hardened leather scale or lamellar armour and mail. Infantry soldiers were more heavily armored than the horsemen. Hauberks and large wooden or wickerwork shields were used as well as long-shafted spears. Infantry spears were about 2.5 meters long and those of the cavalry were up to 5.5 meters long.

Swords used were a short infantry weapon like the Roman gladius and the Sassanid long sword. Both were worn hung from a baldric. Bows were about two meters long when unbraced, about the same size as the famous English longbow, with a maximum range of about 150 meters. Early Muslim archers were infantry archers who proved very effective against the opposing cavalry. The troops at the Sassanid Persian front were lightly armored compared to the Rashidun troops deployed at the Byzantine front.

The battle

The Muslims had encamped at Qadisiyyah with 30,000 men since July 636. Umar ordered Saad to send emissaries to Yasdegerd III and the Persian general Rostam, inviting them to convert to Islam. For the next three months, negotiations between Muslims and Persians continued. On Caliph Umar's instructions, Saad sent an embassy to Persian court with instructions to convert the Sassanid emperor to Islam or to get him to agree to paying Jaziyah. An-Numan ibn Muqarrin led the Muslim emissary to Ctesiphon and met Emperor Yazdgerd III, but the mission failed.

Tactical deployment

During one meeting, Yazdgerd III, intent on humiliating the Muslims, ordered his menials to place a basket full of earth on the head of Asim ibn Amr, a member of the emissary. The optimistic Muslim ambassador interpreted this gesture with the following words: "Congratulations! The enemy has voluntarily surrendered its territory to us" (referring to the earth in the basket). Rustam, the Persian general, held a view similar to Asim ibn Amir. He allegedly rebuked Yazdgerd III for the basket of earth because it signifies that the Persian voluntarily surrendered their land to the Muslims. Yazdgerd III, upon hearing this, called a small band of soldiers to pursue the Muslim emissaries; however, it was too late as the Muslims emissaries had already reached their base camp at that point.

As tensions eased on the Syrian front, Caliph Umar instructed negotiations to be halted. This was an open signal to the Persians to prepare for battle. Rostam Farrokhzād, who was at Valashabad, broke camp for Qadisiyyah. He was inclined, however, to avoid fighting and once more opened peace negotiations. Saad sent Rabi bin Amir and later Mughirah bin Zurarah to hold talks. After the negotiations fell through, both sides prepared for battle. Meanwhile, the Muslims were victorious at the Battle of Yarmouk against the Byzantines.

Day 1

Persian left wing pushed back Muslim's right wing

On 16 November 636, an intervening canal was choked up and converted into a road on Rostam’s orders and before dawn the entire Persian army crossed the canal. Rostam now armed himself with a double set of complete armour and requisite weapons. Both armies stood face to face about 500 meters apart. Rashidun's army was deployed facing northeast, while the Sassanid army had a river at its rear, and was deployed facing southwest.

A cavalry and infantry regiments from Muslim's right center reinforce Muslim's right wing and fight off Persian's left wing

The battle began with personal duels; Muslim Mubarizun stepped forward and many were slain on both sides. Muslim chronicles record several heroic duels between the Sassanid and Muslim champions. The purpose of these duels was to lower the morale of the opposing army by killing as many champions as possible. Having lost several in duels, Rostam began the battle by ordering his left wing to attack the Muslims' right wing.

Persians right wing and right center attacks and drove back Muslim's respective corps

The Persian attack began with heavy showers of arrows, which caused considerable damage to the Muslims' right wing. Then the elephants led a charge. Abdullah ibn Al-mutim, the Muslim commander of right wing, ordered Jareer ibn Abdullah, the Muslim cavalry commander of the right wing, to deal with the Sassanid elephants. As Jareer attempting to halt the advancing elephants, Sassanid heavy cavalry intercepted his force and routed the Muslim cavalry. As the elephants continued to advance, the Muslim infantry began to fall back.

Muslims succeed in routing the Sassanid elephants, following with a two-prong attack on the Persian right wing and right center, with cavalry attacks on the flank and infantry from the rear

Saad sent orders to Ath'ath ibn Qais, commander of the cavalry of right center to check the Sassanid cavalry advance. Ath’ath then led a cavalry regiment that reinforced the right wing cavalry and launched a counterattack at the flank of the Sassanid left wing. Meanwhile, Saad sent orders to Zuhra ibn Al-Hawiyya, commander of Muslims right center, to dispatch an infantry regiment to reinforce the infantry of right wing. An infantry regiment was sent under Hammal ibn Malik that helped the right wing infantry launch a counterattack against the Sassanids. The Sassanid left wing retreated under the frontal attack by infantry of Muslims right wing reinforced by infantry regiment from right center and flanking attack by Muslims cavalry reinforced by a cavalry regiment from right center.

Muslims general attack on the Persian front

With the initial attacks repulsed, Rostam ordered his right center and right wing to advance against the Muslims' elephants on their front. The Muslim left wing and left center were first subjected to intense archery, followed by a charge of the Sassanid right wing and right center. Once again, the Elephant corps led the charge. The Muslim cavalry, on left wing and left center, already in panic due to the charge of the elephants, were driven back by the combined action of Sassanid heavy cavalry and the elephants.

Saad sent word to Asim ibn Amr, commander of the left center, to overpower the elephants. Asim’s strategy was to overcome the archers on the elephants' back and then cut the girths of the saddles. Asim ordered his archers to kill the men on elephants back and infantry men to cut the girths of the saddles, the Muslims' left wing follow suit. The tactic worked, and the Persians retired the elephants to the position behind the front lines, followed by a counterattack of Muslims. The Sassanid army's right center retreated followed by the retreat of the right wing. By afternoon the Persian attacks on the Muslim left wing and left center were beaten back. Saad, in order to exploit this opportunity, ordered a counterattack. The Muslim front moved forward at once. The Muslim cavalry then charged from the flanks with full force, a tactic known as Karr wa farr. The Muslim attacks were eventually repulsed by Rostam, who plunged into the fray personally and is said to have received several wounds. The fighting ended at dusk. The battle was inconclusive, with considerable losses on both the sides. In the Muslim chronicles, the first day of the battle of Qadisiyyah is known as Yawm al-Armath (يوم أرماث) or "The Day of Disorder".

Day 2

On 17 November, like the previous day, Saad decided to start the day with Mubarizuns to inflict maximum morale damages to the Persian army. At noon, while these duelings were still going on, reinforcements from Syria arrived for the Muslim army. First, an advance guard under Al-Qa'qa'a ibn Amr at-Tamimi arrived, followed by the main army under its commander Hashim ibn Utbah, cousin of Saad. Qa’qa divided his advance guard into several small groups and instructed them to reach the battlefield one after the other giving the impression that a very large reinforcement had arrived. Hashim did the same and for the whole day these regiments kept on arriving, which demoralized Persians.

Rustum ordered a general attack on the Muslim front

Qa’qa is that day said to have killed Persian general Bahman, who commanded the Sassanid army at the Battle of Bridge. As there were no elephants in the Sassanid fighting force that day, Saad sought to exploit this opportunity to gain any breakthrough if possible, so he ordered a general attack. All four Muslim corps surged forward, but the Sassanids stood firm and repulsed repeated attacks. During these charges, Qa’qa resorted to the ingenious device of camouflaging camels to look like weird monsters. These monsters moved to the Sassanid front; seeing them, the Sassanid horses turned and bolted. The disorganization of the Sassanid cavalry left their left center infantry vulnerable. Saad ordered the Muslims to intensify the attack. Qa’qa ibn Amr, now acting as a field commander of the Muslim army, planned to kill the Sassanid commander Rostam, and led a group of Mubarizuns, from his Syrian contingent who were also the veterans of Battle of Yarmouk, through the Sassanids' right center towards Rostam's headquarter. Rostam again personally led a counterattack against the Muslims, but no breakthrough could be achieved. At dusk, the two armies pulled back to their camps.

Day 3

Persians attack Muslims using elephant corps

On 18 November, Rostam wanted a quick victory, before more Muslim reinforcements could arrive. The Elephant corps was once again in the front of the Sassanid army, giving them the advantage. Pressing this advantage into service, Rostam ordered a general attack along the Muslim front, using his full force. All four Sassanid corps moved forward and struck the Muslims on their front. The Persian attack began with the customary volley of arrows and projectiles. The Muslims sustained heavy losses before their archers retaliated. The Persian elephant corps once again led the charge, supported by their infantry and cavalry. At the approach of the Sassanid elephants, the Muslim riders once again became unnerved, leading to confusion in the Muslim ranks. The Sassanids pressed the attack, and the Muslims fell back.

Through the gaps that had appeared in the foe's ranks as a result of the Sassanid advance, Rostam sent a cavalry regiment to capture the old palace where Saad the Commander-in-Chief of the Muslim forces was stationed. The strategy of Rostam was that the Muslim Commander-in-Chief should be killed or taken captive with a view to demoralizing the Muslims. However, a strong cavalry contingent of the Muslims rushed to the spot and drove away the Sassanid cavalry.

Persian attack beaten back, with elephants driven off the field for good

Saad determined that there was only one way to win the battle: to destroy the Sassanid elephant corps that was causing the greatest havoc among the Muslim ranks. He issued the orders that the elephants should be overpowered by blinding them and severing their trunks. After a long struggle, the Muslims finally succeeded in mutilating the elephants sufficiently to be driven off. The frightened elephant corps rushed through the Sassanid ranks and made for the river. By noon no elephants were left on the battlefield. The flight of the elephants caused considerable confusion in the Sassanid ranks. To exploit this situation even further, Saad ordered a general attack, and the two armies clashed once again. In spite of the Muslims' repeated charges, the Sassanids held their ground. In the absence of the Persian elephants, the Muslims once again brought up camels camouflaged as monsters. The trick did not work this time, and the Persian horses stood their ground.

The third day of the battle was the hardest for both armies. There were heavy casualties on both sides, and the battlefield was strewn with the dead bodies of fallen warriors. In spite of fatigue after three days of battle, the armies continued the fight, which raged through the night and ending only with the dawn. It became a battle of stamina, with both sides on the verge of breaking. The strategy of Sa'd was to wear down the Persians and snatch victory from them. In the Muslim chronicles the third day of the Battle is known as Yaum-ul-Amas and the night as Lailat-ul-Harir, meaning the "Night of Rumbling Noises".

Day 4

Muslims attack the Persian front, Qa'qa's men penetrated the right center of the Persian army and killed Rustum

At sunrise of 19 November 636, the fighting had ceased, but the battle was still inconclusive. Qa'qa, with the consent of Sa'd, was now acting as a field commander of the Muslim troops. He is reported to have addressed his men as follows:

"If we fight for an hour or so more, the enemy will be defeated. So, warriors of the Bani Tameem make one more attempt and victory will be yours."

The Muslims' left center led by Qa’qa surged forward and attacked the Sassanid right center, followed by the general attack of the Muslims' corps. The Sassanids were taken by surprise at the resumption of battle. The Sassanids left wing and left center were pushed back. Qa’qa again led a group of Mubarizuns against the Sassanids' left center and by noon, he and his men were able to pierce through the Sassanid center.

Muslim attacks were beaten back by the Persians right wing and right center

Final battle

On the final day, Rostam was slain, which heralded the defeat of the Persians. Two different accounts have been told of his mysterious death:

1) Qa'qa and his men dashed towards the Sassanid Headquarter. Meanwhile, in the middle of a sandstorm, Rostam was found dead with over 600 wounds on his body. The Persians were not aware of his death, though, and they continued to fight. The Sassanid right wing counter-attacked and gained its lost position, as the Muslims' left wing retreated back to their original position. The Muslims' left center, now under Qa’qa’s command, when denied the support of their left wing, also retreated back to its original position. Saad now ordered a general attack on the Sassanid front to drive away the Persians, demoralized by the death of their charismatic leader. In the afternoon the Muslims mounted another attack.

2) There was a heavy sandstorm facing the Persian army on the final day of the battle. Rostam lay next to a camel to shelter himself from the storm, while some weapons, such as axes, maces, and swords had been loaded on the camel. Hilāl ibn `Ullafah accidentally cut the girdle of the load on the camel, not knowing that Rostam was behind and under it. The weapons fell on Rostam and broke his back leaving him half dead and paralyzed. Hilal beheaded Rostam and shouted "I swear to the god of Kaaba that I have killed Rostam." Shocked by the head of their legendary leader dangling before their eyes, the Persians were demoralized, and the commanders lost control of the army. Many Persian soldiers were slain in the chaos, many escaped through the river, and finally the rest of the army surrendered.

3) A version from Ya'qubi records that Dhiraar bin Al-Azwar, Tulayha, Amru bin Ma'adi Yakrib and Kurt bin Jammah al-Abdi discovered the corpse of Rostam Farrokhzād

Persians retreating across the river

The Sassanid front, after putting up a last resistance, finally collapsed; part of the Sassanid army retreated in an organized manner while the rest retreated in panic towards the river. At this stage Galinus took command of what was left of the Sassanid army and claimed control of the bridge head, succeeding in getting the bulk of the army across the bridge safely. The battle of Qaddisiyyah was over, and the Muslims were victorious. Saad sent the cavalry regiments in various directions to pursue the fleeing Persians. The stragglers that the Muslims met along the way were either killed or taken captive. Heavy casualties were suffered by the Sassanids during these pursuits.

Aftermath

From this battle, the Arab Muslims gained a large amount of spoils, including the famed jewel-encrusted royal standard, called the Derafsh-e-Kāveyān (the 'flag of Kāveh'). The jewel was cut up and sold in pieces in Medina. The Arab fighters became known as ‘’ahl al-Qādisiyyah’’ and held the highest prestige of the later Arab settlers within Iraq and its important garrison town, Kufa.

Once the battle of Qadisiyya was over, Sa'ad sent a report of the Muslim victory to Umar. The battle shook the Sassanian rule in Iraq to its foundations but was not the end of their rule in Iraq. As long as the Sassanids held their capital Ctesiphon, there was always the danger that at some suitable moment they would make an attempt to recover what they had lost and drive away the Arabs from Iraq. Caliph Umar thus sent instructions to Saad that as a sequel to the battle of Qadisiyyah, the Muslims should push forward to capture Ctesiphon. The Siege of Ctesiphon continued for two months, and the city was finally taken in March 637. Muslim forces conquered the Persian provinces up to Khuzistan. The conquest was slowed, however, by a severe drought in Arabia in 638 and the plague in southern Iraq and Syria in 639. After this, Caliph Umar wanted a break to manage the conquered territories and for then he wanted to leave rest of Persia to the Persians. Umar is reported to have said:

"I wish there were a mountain of fire between us and the Persians, so that neither they could get to us, nor we to them."

The Persian perspective however, was the polar opposite, one of great embarrassment, humiliation, and scorn. The pride of the imperial Sassanids had been hurt by the conquest of Iraq by the Arabs, and they continued the struggle to regain the lost territory. Thus a major Persian counterattack was launched and subsequently repulsed at the Battle of Nahavand, fought in December 641.

After that, a full-scale invasion of the Sassanid Persian empire was planned by Umar to conquer his arch-rival entirely. The last Persian emperor was Yazdgerd III, who was killed in 653 during the reign of the Caliph Uthman. His death officially marks the end of the Sassanid royal lineage and empire.

See also

• Modern usage of al-Qādisiyyah
• Islamic conquest of Persia
• Muslim conquests
• Sassanid Empire
• Shāh-nāmeh