Fall of The Sassanid Empire - Military

Military

Years of warfare between the Sassanids and the Byzantines, as well as the strain of the Khazar invasion of Transcaucasia, had exhausted the army. No effective ruler followed Khosrau II and this created chaos in society and problems in the provincial administration (until Yazdegerd III came to power). All these factors undermined the strength of the Persian army. Yazdegerd III lacked experience and didn't try to rebuild the army.

When Arab squadrons made their first raids into Sassanid territory, Yazdegerd III didn't consider them a threat, and he refused to send an army to encounter the invaders. When the main Arab army reached the Persian borders, Yazdegerd III procrastinated in dispatching an army against the Arabs. Even Rostam-e Farokhzad, who was both Eran Spahbod and Viceroy, didn't see the Arabs as a threat. Without opposition, the Arabs had time to consolidate and fortify their positions.

When hostilities between the Sassanids and the Arabs finally began, the Persian army faced fundamental problems. While their heavy cavalry had proved effective against the Roman armies, it was too slow and regimented to act with full force against the agile and unpredictable lightly armed Arab cavalry and foot archers.

The Persian army had a few initial successes. War elephants temporarily stopped the Arab army, but when Arab veterans returned from the Syrian fronts where they had been fighting against Byzantine armies, they taught the Arab army how to deal with these beasts. Thus war elephants had lost their effectiveness on the battlefield.

These factors contributed to the decisive Sassanid defeat at the Battle of al-Qādisiyyah. The Persians, who had only one generation before conquered Egypt and Asia Minor, lost decisive battles when nimble, lightly armed Arabs accustomed to skirmishes and desert warfare attacked them. The Arab squadrons defeated the Persian army in several more battles culminating in the Battle of Nihawānd, the last major battle of the Sassanids. The Sassanid dynasty came to an end the following year with the death of Yazdegerd III.