Qadisiyya: the four days that broke Persia

Umar sent Sa'd ibn Abi Waqqas with 30,000 men against a Sasanian army of perhaps 100,000, elephants, and the general Rustam. Sa'd, sick with a boil that prevented him from mounting a horse, commanded the battle from a stretcher on a rooftop. Persia fell in four days.

In 14 AH (635 CE) Umar ibn al-Khattab decided that the pressure of the Sasanian Empire on the eastern frontier of the caliphate could not be sustained by defensive operations alone. He resolved on a full campaign to break the Sasanian field army. He needed a commander for the campaign whom he trusted absolutely.

He appointed Sa'd ibn Abi Waqqas, one of the ten Companions promised paradise, veteran of Badr, Uhud, the Trench, and Khaybar, personal favourite of the Prophet ﷺ who had said to him "Shoot, Sa'd. May my father and mother be sacrificed for you." Sa'd was in his early forties. He had never commanded an army of that size before.

He was given an army of about 30,000. It was drawn from the tribes of the Arabian peninsula. Many of the men had never fought in a formal pitched battle. Sa'd marched them slowly, drilling them, from Medina to the frontier. He reached the town of Qadisiyya on the edge of the Iraqi alluvial plain in late 636 CE.

Facing him across the plain was the Sasanian army under the command of Rustam Farrukhzad, the greatest general of the empire. Rustam's army is variously estimated at between 60,000 and 100,000. He had 33 war elephants, creatures the Arab cavalry had never faced. He had the elite Immortals. He had the imperial banner of the Sasanians, the Derafsh Kaviani, embroidered with jewels, said to have been made from the leather apron of a legendary blacksmith who had led a revolt against the tyrant Zahhak in the mythic Persian past.

Sa'd fell ill on the eve of the battle. He developed a large boil on his hip that made it impossible for him to sit on a horse. He was in serious pain. He could barely walk. He wept in his tent at his condition. He wanted to lead the battle. He could not.

The first day, Yawm Armath, was inconclusive. The Muslim cavalry could not close with the Persian line because the elephants panicked their horses. Fighting went on until dark. The Muslims camped in their positions.

The second day, Yawm Aghwath, a Muslim relief column arrived from Syria under al-Qa'qa' ibn Amr, a veteran of Yarmouk. Al-Qa'qa' organised his men into small groups of horsemen and sent them in one after another all day, so that Rustam saw a constant stream of "reinforcements" arriving and could not tell when they would end. The Muslim army had actually only been reinforced by a few thousand. The psychological effect of the appearance of continuous reinforcement was enormous. The Persian line began to waver.

The third day, Yawm Amas, Sa'd's men addressed the elephant problem. They chose their best marksmen and armed them with long spears and short-throw javelins. The marksmen were told to target only two points: the trunks and the eyes of the elephants. It worked. The lead elephant, wounded in the eye and trunk, turned and stampeded through its own line. The remaining elephants broke. Rustam's front collapsed in confusion.

The fourth day, Yawm al-Qadisiyya, was decisive. A dust storm blew up from the west, straight into the Persian faces. The Muslim army, wind at their backs, drove forward through the storm. Rustam was killed in the chaos. His head was cut off. The Derafsh Kaviani, the imperial banner, was taken and stripped of its jewels. The Sasanian army broke and fled toward Ctesiphon. Persia lost the war in four days.

Sa'd, still on his stretcher, was told the battle was won. He wept and made sujud on the roof. The Sasanian capital Ctesiphon fell within weeks. The imperial treasury was captured. The Persian empire that had stood against Rome for four hundred years collapsed within a season.

Sa'd founded the garrison city of Kufa on Umar's instruction. He served as governor. When he died in 674 CE, aged nearly 80, he had outlived Umar, Uthman, and Ali. He was the last of the ten promised paradise. He was buried in his simple estate outside Medina in a shroud he had kept for years, a shroud made from a mantle he had worn at Badr.

What the story teaches

Qadisiyya is remembered because it settled the question of whether a Muslim army could break a great imperial field army, in pitched battle, on the enemy's own ground, against elephants and Immortals and prepared positions. The answer, over four days in November 636 CE, was: yes. The classical Muslim historians take specific lessons from the battle. First, that Sa'd's illness was not fatal to command, command in Islam is not equivalent to physical presence on the front line, and a commander wounded or immobilised who continues to think clearly is more valuable than a commander who dies in the first charge. Second, that psychological warfare, al-Qa'qa's staggered reinforcement arrivals, is a legitimate and decisive tool. Third, that Allah grants tools to those who ask for them, the dust storm on the fourth day, blowing into Persian eyes, is remembered by the classical scholars as answered du'a. Fourth, that against a technological asymmetry, one adapts. The Muslim spearmen adapted to elephants by targeting eyes and trunks. Modern Muslim armies fighting against modern technological asymmetries have taken this specific example forward for centuries.