The Battle of Chains was fought in April 633 AD between the armies of the Arab Rashidun Caliphate and the Persian Sassanid Empire during the Muslim conquest of Persia.
The Arab general Khalid ibn al-Walid led his army of 18,000 troops north from his Arabian base at Yamama to invade Persian Mesopotamia on the orders of Caliph Abu Bakr in March 633. His attempts to convince the Persian Governor of Dast Meisan, Hormozd, to surrender were fruitless, and Hormozd instead called for reinforcements from Shah Yazdegerd III. Hormozd then left the provincial capital of Uballa to assemble his men, allowing for Khalid to threaten the town of Hufair and lure Hormozd into a battle. Ultimately, he positioned himself to the south of the town of Kazima. The battle came to be known as "Chains" due to the lines of the disciplined Sassanid infantry who faced the Arabs.
Khalid forced the Sassanids to form up to the west of Kazima at the end of a tiring march, and both armies formed up with infantry in the center and cavalry on the wings. The Arabs took up positions on the hilltops, overlooking the sun-baked Sassanids, who guarded the only spring in the area. Hormozd challenged Khalid to a duel, and they fought to a standstill until the Sassanids sent in two more champions. The Arab general al-Qaqa ibn Amr al-Tamimi charged into battle, and Qaqa and Khalid killed Hormozd and his fighters. The Arab generals then returned to their lines and ordered an attack, and the Muslim infantry attack initially stalled. However, the well-rested Arabs eventually tired out the Sassanids with several charges, cracking the disciplined Sassanid center. The leaderless Sassanid army soon collapsed, as the wing commanders Qubad and Anoshagn withdrew with their horses. The Sassanid center was then enveloped, and the Muslims were victorious. Half of the Sassanid army was lost, while the Muslims lost, at most, a few thousand men.