The Battle of al-Ubulla was fought in 634 between the armies of the Arab Rashidun Caliphate and an army led by the Sassanid client king Alzec of the White Huns. The Rashiduns repelled a ferocious assault on the port city of al-Ubulla, suffering heavy losses at the hands of the White Huns' elephants before turning the tide and smashing the invading army.
The White Huns had been subdued by Shah Khosrau II of Persia in 607, and, when the Rashidun Caliphate declared war on the Sassanids in 633, the Rashiduns were joined by their client states, the White Huns, the Kidarites, and Sindh. As the Arab armies conquered Mesopotamia, the White Hun ruler Alzec assembled an army of 618 troops, including Sogdian footmen, Hunnic cavalry, and Asian war elephants. His 618-strong army attacked the Mesopotamian port city of al-Ubulla, expecting that it was undefended due to Shurahbil ibn Hasana's march north to Ctesiphon. However, the Arabs had built up a new army led by Sa'd ibn Abi Waqqas with the goal of conquering southern Iran and defending the Arabian border, with this army consisting mostly of poorly-armored spearmen and horsemen. The Hunnic king was confident that he could crush the Rashidun army and the town militia in al-Ubulla, especially once he fielded his fearsome elephants.
The Rashiduns deployed in two sections to block off the two main streets in the town's northeast, holding two regiments of swordsmen and some cavalry in reserve in the center. The White Huns attacked both of these forces, sending their cavalry to attack the Arab right flank as the war elephants tore through the Arab left flank. The Arab spearmen were trampled and mangled by the elephants, but Sa'd desperately sent in his cavalry and reserves to attempt to kill the elephants and their mahouts as quickly as possible. Ultimately, sheer strength of numbers led to the Arabs prevailing and annihilating the elephant unit, upon which the Arab left flank left the town and attacked the White Hun infantry and cavalry assault force from the rear. Meanwhile, the Arab cavalry returned to the center of town to aid Sa'd in fighting off Hunnic cavalry who had attempted to claim his head. Ultimately, the Arabs won a surprising victory, crushing the force sent to attack them, despite losing a third of their number. King Zoltan of Sogdia, the new Hunnic ruler, proceeded to withdraw the crippled Hunnic army back into Persia, hoping to save it from annihilation.