The Battle of Walaja was fought between the armies of the Arab Rashidun Caliphate and the Persian Sassanid Empire in May 633 AD during the Muslim conquest of Persia.
Emperor Yazdegerd III summoned armies from the northern and eastern frontiers of the empire to deal with the Muslim threat in southern Mesopotamia, sending Andarzaghar with 25,000 troops to guard the town of Walaja and Bahman Jadhuyih to protect al-Hira and reinforce Andarzaghar if necessary. The Arab general Khalid ibn al-Walid led his 15,000-strong army north to defeat the Persian armies separately, engaging Andarzaghar at Walaja.
The Arabs rested for two days after their forced march, but Khalid decided to attack before Bahman's reinforcement army could arrive. He met the Persians on an even plain, and his army consisted entirely of footmen; the Persians waited in an impregnable defensive position, with its rear guarded by a cliff. The Arabs charged into the Persian ranks, and they fought to a standstill. The tired Sassanid frontline was replaced by fresh troops, and Andarzaghar's counterattack began to push the tired Muslims back towards a ridge, where retreat would be impossible. Khalid then sent cavalry hidden in the desert to attack the Sassanids from the eastern ridge; the Sassanid rear was now undefended, and the Sassanid army was smashed. Andarzaghar was killed, and only 5,000 of his men escaped the defeat.