After Hirah, what? With the conquest of Hirah, Khalid had achieved the objective that Abu Bakr had set for him. Having succeeded in his objective, a man like Khalid could not be expected to rest on oars. The question before Khalid was: after Hirah, what next? After taking stock of the situation around him, Khalid decided to advance further afield.

Anbar. Khalid chose Anbar as his next objective. It was an important town and commercial center to which caravans came from Syria and Persia. It was towards the end of June 633 C E. that Khalid marched with his army from Hirah to Anbar. The Muslim force marched along the west bank of the Euphrates, and crossed the river somewhere below Anbar.

Anbar was the headquarter town of the district of Sabat. The Governor of the district was Sheerzad, and he decided to defend the town with the help of his Persian garrison and the Arab auxiliaries. The town was protected by walls, and a large deep moat.

The battle. The town of Anbar was situated at a height, and the Muslim army had to camp at the low plain below the town. As the Persians saw the height that intervened between them and the Muslim army, they felt that their position was invulnerable. The Persians stood on the top of the walls of the citadel carelessly in groups looking at the Muslim army as if they were watching a tournament.

Khalid collected the best of his archers, and commanded them to shoot at the eyes of the Persians. The Muslim archers shot several rounds, and as a result thousands of Persians lost their eyes. Because of this action the battle of Anbar came to be called 'the battle of the eyes'.

The fall of Anbar. As a result of the efforts of the Muslim archers, a panic was created in the ranks of the Persians, and Sheerzad sent an offer to negotiate terms. Khalid rejected the offer and demanded that the surrender should be unconditional. Under the circumstances, Sheerzad decided to continue resistance.

The moat stood between the Persians and the Muslims, and the problem before Khalid was to cross the moat. Khalid selected a point where the moat was the narrowest. Here he placed his archers in position to shoot at the enemy ruthlessly. Under the cover of these archers Khalid pushed his army. The old and weak camels of the army were slaughtered and dumped into the moat. As the pile of carcasses rose, it formed a bridge over which the Muslim army crossed the moat and assaulted the fort.

Finding his position insecure, Sheerzad made another offer to surrender provided the Persian army was allowed to withdraw in safety. Khalid agreed to the offer provided the Persians did not carry any arms or other property with them.

Withdrawal of Sheerzad. Sheerzad accepted the terms given by Khalid. The Persian soldiers and their families evacuated the fort at Anbar, and left for Al Madain. Thereafter the Muslims occupied the town of Anbar. The Christian Arabs, the auxiliaries of the Persians had no option but to lay down arms after the withdrawal of the Persian forces. They agreed to pay Jizya. Khalid stayed at Anbar for a few days, and received the submission of the clans living in the neighborhood.

When Sheerzad reached Al Madain, he was severely rebuked by the Persian military authorities at his failure to defend Anbar. He attributed his failure to the betrayal of the Christian Arabs. He said, "I was among a people whose roots were among the Arabs, and their resistance to the invading Muslim Arabs was half hearted."