Simultaneous invasions began in 633, with armies heading west into Syria and north into Persia (modern Iraq). The western campaigns had little to note until after Khalid’s eastern army joined them, so we’ll start with Khalid. He was in northern Arabia with his army, having just conquered the last of the rebellions in eastern and northern lands. He left the city of Yamamah and headed north to join a former Ridda Wars rebel who was now raiding southern Iraq in the name of the Caliph Abu Bakr.
Hugh Kennedy, in Great Arab Conquests, describes how it took about three weeks’ riding across the northern Arabian desert from Medina to reach southern Iraq, where suddenly there is plentiful water. “In many places the border between the irrigated lands and the desert is clear and precise: you can virtually stand with one foot on either side of this environmental frontier.” Khalid’s army had a head start on the journey, and they had already been fighting against—and co-opting—-some of the Arab tribes who lived on the border of the irrigated lands. His core army from Yamamah may have been small, about 1000 men. But he added more fighters as he went, bringing border tribesmen with him.
The fortresses that ran up the south side of the Euphrates River from the Persian Gulf were small and lightly manned. Siege warfare depended on holding out until a larger force came to chase away the besiegers, and everyone knew that no larger army would be coming. So each conquest was a combination of force and negotiation. The “Persian” troops were mostly local Arabs who had become regulars for the regime. The locals were happy to see their Persian overlords displaced.
The first battle was named “The Battle of Chains” by the Muslims, because the Persian fighters were rumored to be chained together to prevent flight. It was fought at Uballa, a port on the Tigris River near the Persian Gulf. All of the four main battles with Persians are recorded in Muslim sources as having been fought against great numerical odds. They also began all of the battles with challenges to single combat, which was the Arab model of battle that we saw in the Battles of Badr and Uhud. Khalid challenged the commander to fight him, and he is recorded as always winning these duels.
Losing fighters fled each battle upriver, where they were collected into the next force to face the Muslims. Khalid’s men moved quickly, going up the Euphrates River within a few months. Their speed forced the Persians to move faster than they were set up to move, so they arrived at battles exhausted. The fourth battle of this type was probably the largest, and it resulted in vast casualties on both sides. It’s hard to know how much to tell about such battles; of course, each one cries out for attention with its particular story, but the next set of years are so chock full of battles that only the really unusual ones are worth telling. Be it noted: the locals and some imperial troops from Ctesiphon did try to stop them at times. But although they had the home advantage and sometimes greater numbers, they lost every encounter.
The last one, the Battle of Ullais, took out the largest army the Persians could manage at that time. Muslim records suggest as many as 70,000 fighters on the Persian side lost their lives, and one of their stories explains how Khalid beheaded a large number of them by a tributary of the Euphrates until it ran red. After that, there wasn’t any organized resistance.
The city of Hira, halfway up the river, was Khalid’s target. It was the capital of the Arab buffer state ruled by the Lakhmids, whose job it was to hold the frontier against the matching Roman Arab buffer state, ruled by the Ghassanids. The Muslim Arabs wanted to capture both capitals so that all of the Arabs would be under their rule.
Hira was a city on the model of Medina: it was a collection of fortified houses and palaces, without a wall around the city limits. Everything was made from mud brick, since it was not a region with much stone; buildings could go up to two stories and not much more. Clan chiefs lived in walled houses/palaces, and among these fortifications, there were also monasteries and churches, as well as ordinary village dwellings. Hira had a Nestorian bishop; the Lakhmids had generally converted to Christianity.
In Hira, the clans pulled inside their fortresses, while the small fry watched Khalid’s men moving freely through the unwalled spaces. The leaders cared most about their castles and churches, and they knew no army was coming to their relief. They negotiated with Khalid for an amount of tribute to pay in exchange for nothing being ruined. Hira collected taxes from other towns on the southern Euphrates, so tribute from Hira had the potential to add up. Khalid sent the first tribute from a Persian zone to Medina.
After Hira, Khalid went north to Anbar, where he again conquered. But instead of setting out to conquer more of Persia, Khalid received orders to head to Syria. The Lakhmid towns along the Euphrates were being easily held by Muslims, but the Ghassanid towns of Syria were causing more of a problem to the commanders who had been sent in that direction. So the Muslim invasion of Mesopotamia ended for now.
- The War of the Three Gods, by Peter Crawford.
- The Great Arab Conquests, by Hugh Kennedy