Rashidun forces under Khalid ibn al-Walid defeated a Sasanian field army and allied contingents at Walaja in Mesopotamia, an early turning point that helped destabilize Sasanian control in Iraq.
Rashidun forces captured al-Hirah on the Euphrates, weakening Sasanian frontier defenses and improving the attackers’ access to routes toward the Sasanian heartland and Ctesiphon.
A Sasanian counteroffensive defeated the Rashidun army at the Battle of the Bridge (al-Jisr) near the Euphrates—traditionally remembered as the only major Sasanian battlefield victory over the Rashidun forces in the Iraq campaign.
Rashidun forces under al-Muthanna ibn Haritha defeated a Sasanian army at Buwayb, reversing momentum after the earlier defeat at the Bridge and helping reassert the Muslim position in Iraq.
Rashidun forces defeated a major Sasanian army at al-Qadisiyyah, a decisive engagement that opened the way to the Sasanian capital region and marked the beginning of the end for Yazdegerd III’s dynasty.
Rashidun forces besieged and captured Ctesiphon (al-Madā’in), the Sasanian imperial capital complex, consolidating control over Mesopotamia and further undermining Sasanian administrative and military coordination.
Soon after the fall of Ctesiphon, Rashidun forces defeated Sasanian troops at Jalula, helping secure approaches toward the Zagros and facilitating subsequent operations deeper into Iranian territory.
An early Rashidun naval expedition from Bahrain attempted to invade Pars/Fars in 638/639 but failed; later campaigns renewed pressure on the province and contributed to its eventual subjugation.
At Nahavand, Rashidun forces defeated a major Sasanian army in a battle widely treated as a decisive turning point, after which organized Sasanian resistance largely collapsed and the conquest accelerated across Iran.
Rashidun forces defeated Sasanian troops in the Spahan/Isfahan region, a step in extending control into central Iran after Nahavand and in fracturing remaining Sasanian provincial defenses.
In the final campaigns in Fars, Rashidun forces captured and sacked Estakhr (Istakhr) after renewed resistance; accounts report very heavy losses among defenders, signaling the collapse of effective Sasanian control in the province.
Fighting at Ray occurred during the closing phase of the conquest; the battle is described as part of the turbulent endgame involving Sasanian remnants and local Iranian noble factions as Rashidun authority expanded.
Yazdegerd III, the last Sasanian shah (r. 632–651), was killed in 651 (near Marw/Merv), an event conventionally taken as the definitive end of the Sasanian Empire and of pre-Islamic imperial rule in Iran.
The Fall of the Sasanian Empire and the Arab Conquests (633–651)
