Abbasid civil war (865–866)

Neither caliph participated in the direct military operations of the war. In Al-Musta'in's case, he was generally content to leave the responsibility of conducting the war effort to Muhammad b. 'Abdallah. As commander, Muhammad opted for an overall defensive strategy. Relying on his position in Baghdad, he was reluctant to engage in any sort of offensive operations outside the city and its surrounding districts, even when he was advised by others to do so. While he did make an effort to securing the nearby towns that controlled access to the city, there is no mention of any attempt to attack Samarra. By staying within Baghdad and keeping the city's supply routes open, while at the same time cutting off foodstuffs and tax receipts meant for Samarra, Muhammad likely believed that he could outlast al-Mu'tazz's armies.

A massive amount of work was done to prepare Baghdad for a siege. Walls and trenches were constructed on both the east and west sides of the city, at a cost of over three hundred thousand dinars. Ballistas and mangonels were installed on the walls, and "war engines" designed to hinder enemy movement were placed in front of the city gates. The market awnings were removed so as to prevent them from being set on fire, and the areas outside the city were ploughed so that the mud would entrap the attackers.[16] A few days after the fighting began, Muhammad ordered the razing of a large area behind the walls, so that the defenders would have more room to operate in.

Muhammad had numerous sources of manpower in his allies and in the people of Baghdad. He could rely on many friendly military commanders to heed his call for assistance, and in the early months of the war several small regiments from Iraq, the Jazira, the Jibal, the Arab-Byzantine frontier and elsewhere arrived in Baghdad.[17] Muhammad also had an ally in his nephew Muhammad b. Tahir, who was the governor of most of the eastern provinces, although at the time the latter was largely preoccupied with the rebellion of Hasan b. Zayd in Tabaristan.[18] In order to augment the ranks of his soldiers, Muhammad instituted a draft in Baghdad and called on for volunteers to serve al-Musta'in. A group of Khorasani pilgrims en route to Mecca at the time the war began were asked to stay and fight. Many of the city's brigands were also recruited and provided with weapons. At first they were given mats to protect themselves and bags of rocks or bricks to attack the enemy with;[19] later they were given clubs, placed under their own chief and registered in the military roll so that they could be paid.[20] Arab Bedouins and Kurdish tribesmen from the surrounding regions also fought for al-Musta'in.[21]

In keeping with normal Abbasid court practice,[22] gifts were routinely bestowed upon officers and soldiers by both al-Musta'in and Muhammad. Tabari's narrative of events contains numerous instances of commanders being rewarded for their service. They were given gifts on a number of occasions, such as their initial arrival in Baghdad with their troops, distinguishing themselves on the battlefield, or being selected to lead an important mission. Traditional robes of honor were regularly given out; other gifts included jewelry, ceremonial swords, money, and increased allotments for the troops.[23]

The exact size of the army under Muhammad's command is not explicitly stated, but it was likely much greater than al-Mu'tazz's forces.[24] As many of his units were irregulars, however, their conduct in battle was not always reliable, and they were disciplined often for their failure to follow orders. In addition, while many army commanders were willing to pledge themselves to al-Musta'in's cause, not all of them were willing to take orders from Muhammad; there are multiple instances of pro-Musta'in regiments outside Baghdad acting independently and engaging the Turks on their own initiative.

From the start of the crisis, al-Mu'tazz was concerned with portraying himself as the legitimate caliph. He had been proclaimed as heir-apparent during his father's lifetime, and according to the succession arrangements he should have become caliph after the death of al-Muntasir. When he had signed away his rights to the caliphate in 862, he had been under duress to do so, with the Turks threatening to kill him if he refused, and therefore he considered the deed of abdication to be void. He also sought to convince the people that they could switch their allegiance to him without breaking the oath they had taken to serve al-Musta'in, and went through the effort to explain in detail how this could be done in a letter to Muhammad b. 'Abdallah.[13]

Al-Mu'tazz was initially accommodating toward those in Samarra who opposed his bid for the caliphate, and did not compel anyone to swear the oath to him if they refused to do so.[25] He did, however, write to commanders stationed throughout the empire requesting their support, and soon reinforcements were arriving in Samarra.[26] As the conflict progressed, he steadily gained followers as members of al-Musta'in's camp began to defect to him.[27] He also made efforts to entice al-Musta'in's officers, writing offers to them and promising substantial rewards if they would switch their allegiance to him.[28]

Al-Mu'tazz's brother Abu Ahmad was put in charge of the Samarran forces at the beginning of the war. He was charged by the caliph with defeating al-Musta'in and Muhammad b. 'Abdallah, and was given the authority to command the army in any manner he pleased.[29] Abu Ahmad's overall strategy was to keep Baghdad under constant attack from his troops, and to gain the surrender of the city by either assaulting it or starving its inhabitants until they lost the will to fight any longer. Toward this end, al-Mu'tazz sent armies to secure the neighboring towns that controlled access to Baghdad, and Abu Ahmad attempted to halt and seize any revenue shipments heading toward the city.[30] The way in which Abu Ahmad ran the siege was not unquestionably accepted by al-Mu'tazz, who reportedly wrote him a letter in the middle of the war complaining of his lack of progress in forcing al-Musta'in's capitulation,[31] but he remained in command of the main besieging force throughout the entire conflict.

Abu Ahmad's army at the beginning of the siege numbered approximately 7,000 soldiers. Additional troops sent from Samarra a short time later increased its size to 11,000, though a large number of the reinforcements were killed soon after their arrival.[32] At a later point in the war, a spy for Muhammad b. 'Abdallah reported that the besieging armies on the East and West sides of Baghdad totaled 19,000 men, and that al-Mu'tazz had very few additional troops to put in the field, since Samarra had been almost completely emptied of soldiers.[33]

Northern Baghdad as it existed at the time of the siege, showing the location of the walls of al-Musta'in

For the first few days after the arrival of Abu Ahmad and his army before the gates of Baghdad, the two sides refrained from directly engaging each other in combat. On March 14, Muhammad b. 'Abdallah approached the enemy camp and called on the Samarrans to depart; if they did, he guaranteed that al-Musta'in would recognize al-Mu'tazz as heir-apparent. If they refused to leave, however, Muhammad intended to initiate hostilities the following morning.[35]

The next day, the Samarrans approached the Shammasiyyah and Khorasan gates along the eastern wall and attempted to force their way through them. The Baghdadis responded by firing upon them with arrows, mangonels and ballistas, inflicting heavy casualties upon the attackers. At the Khorasan Gate, the Turks attempted to move up an artillery piece into firing range, but a charge by the regular and irregular Baghdadi forces dislodged the enemy from their position. By the end of the day, the Samarrans withdrew back to their camp; both sides had sustained hundreds of casualties from the fighting.[36]

On March 20 a second army sent from Samarra, consisting of 4,000 Turks, North Africans and Ferghanans, arrived in front of the western side of Baghdad and made camp near the Gates of the Fief and Qatrabbul. The next morning, Muhammad b. 'Abdallah ordered a large contingent of infantry and cavalry to battle them. At first the Samarrans had the upper hand, and were able to force the Baghdadis into a narrow area near the Gate of the Fief. Baghdadi reinforcements soon arrived, however, and the combined forces were able to drive the Samarrans back. Having gained the initiative, the defenders charged and forced the Samarrans to retreat to an area where yet another Baghdadi force lay in ambush. At this point, the Samarran retreat turned into a rout, and the troops began to flee for their lives. Many attempted to swim across the Tigris to Abu Ahmad's camp, but were seized by boats patrolling the river. The rest turned north, with some of the soldiers going all the way back to Samarra.

The battle for the Qatrabbul Gate had been a massive victory for the Baghdadis. Of the four thousand Samarrans stationed on the western side of the city, two thousand of them had been killed, with several of their heads being hung around Baghdad, and many others were taken prisoner.[32] In Samarra, news of the defeat was met with rioting; many among the populace apparently considered the battle to be a sign of the weakness of al-Mu'tazz's forces.[37] Muhammad b. 'Abdallah, however, refused to follow up on his victory. Rejecting the council of his advisors to press his advantage and pursue the fleeing soldiers, his only order after the battle was to have proclamation of victory drawn up and read in the Jama Mosque of the Round City.[38] Meanwhile, Abu Ahmad's army, which is not mentioned as having participated in the battle that day, remained encamped on the eastern side. As a result, the siege of the city continued.

After the battle for the Qatrabbul Gate, the siege effectively turned into a stalemate. Throughout the late spring and summer, the Samarrans and Baghdadis regularly engaged each other around the defensive fortifications of the city and inflicted many casualties on each other, but neither side was able to gain a clear advantage.[39] Over the following months, the fighting spread to the districts neighboring Baghdad, as both sides fought to control the routes leading into the city. The Samarrans were able to limit the level of supplies reaching the defenders, but were unable to prevent the Baghdadi armies from moving in and out of the city.

The stalemate around Baghdad remained unbroken until early September. On the morning of September 8, however, the Samarran armies on both sides of the city engaged in a major assault on the fortifications. While the Samarrans on the eastern side attacked the Shammasiyyah Gate, the Turks and North Africans on the western side managed to punch through the initial line of defenses and advance to the Anbar Gate. Despite being caught unaware, the defenders at the Anbar Gate put up a staunch resistance, but eventually they were forced to retreat and the Anbar Gate was set on fire. The Samarrans then entered Baghdad and spread throughout the Harbiyah quarter of the city, setting fire to the areas that they entered. The residents of the neighborhoods that the Samarrans passed through fled for their lives, and the Samarran troops planted flags in the parts of the city that they conquered.

In response to the assault Muhammad b. 'Abdallah gathered his commanders together, and then sent men to the gates all along the western side of the city. The reinforcements engaged the Samarrans and, after killing a large number of them, forced them back to the gateways. Fighting continued until the late afternoon, with the defenders finally managing to expel the Samarrans from the gates and forcing them to flee back to their camp. The areas in the wall where the Samarrans had broken through were ordered repaired. The assault on the eastern side of the city also failed, as the Baghdadis were able to force the attackers back. As with the fighting on the western side, many Baghdadi and Samarran soldiers were killed in the battle for the Shammasiyyah Gate.[40] The assault having therefore failed, the Samarrans returned to their siege positions.

As the siege continued into autumn, Muhammad worked with his lieutenants to plan a sally in an attempt to break the stalemate. The mangonels and ballistas along the walls were prepared for action, and in late November the city gates were opened. The entire Baghdadi army then came out of the city, while river boats loaded with bowmen and artillery moved up the Tigris. They attacked the Samarran army and routed them, forcing them to flee. The Samarran camp was plundered and the irregulars began cutting off the heads of the slain. The Samarran position was saved only when Abu Ahmad made a stand and rallied the troops to regroup; at the same time, the Baghdadis lost their focus and their charge stalled. The Samarrans soon returned to their camp, while the Baghdadis retreated back to the city.[41]

The town of al-Nahrawan lay just to the east of Baghdad. Its importance lay in the fact that it was the first stage on the road from Baghdad to Khorasan,[42] the latter of which was governed by Muhammad b. 'Abdallah's nephew; whoever controlled the town would therefore be able to stop or allow transportation between the two locations.

Before the siege of Baghdad began, Muhammad b. 'Abdallah sent five hundred infantry and cavalry to al-Nahrawan to defend it against the Turks. Later, another seven hundred soldiers were dispatched to the town to reinforce the first group. On March 19, nine days after Abu Ahmad had arrived in front of Baghdad, a force of Turks marched to al-Nahrawan challenge Muhammad's control of it. The defenders decided to meet the Turks on the field, and a battle ensued. The Turks soon gained the upper hand, and the defenders turned and fled to Baghdad. Fifty of the defenders had died in the battle, and the Turks sent their heads to Samarra, along with mounts and weapons that the defenders had abandoned. With the Turks victorious, they gained control of the Khorasan road, and traffic between there and Baghdad was cut off. When Muhammad learned of the defeat, he recalled troops stationed further down the road at Hamadan and ordered their return to Baghdad.[43]

Although Muhammad is not recorded as having made any attempts to retake al-Nahrawan, the town continued to suffer during the conflict. At some date after the battle, a group of Samarrans returning from deployment in the Jibal entered al-Nahrawan. For unstated reasons, the Samarran commander ordered his troops to plunder the town. The soldiers then began attacking the local residents, and most of the citizens were forced to flee.[44]

Al-Anbar, lying on the Euphrates to the west of Baghdad, was a major town in the early Abbasid era.[45] At the outbreak of hostilities, Muhammad b. 'Abdallah ordered its ruler to prepare for its defense. The canals and bridges around the town were cut, and the surrounding area was turned into a large swamp. By the middle of spring the commander of al-Anbar had raised a force of several thousand Bedouin recruits, and he sent a request to Muhammad for reinforcements. Muhammad promptly ordered over a thousand more cavalry and infantry to depart for the town.[46]

In Samarra, meanwhile, plans were developed to attack al-Anbar, and soon al-Mu'tazz sent a force of Turks and North Africans under Muhammad ibn Bugha to take the town. The defense at al-Anbar was split into two groups, with the reinforcements stationed outside the town and the Bedouins within. When the Samarran army arrived before al-Anbar, they caught the reinforcements by surprise and quickly fell upon them. Some of the defenders put up a fight, but they soon fled, with many of them killed or becoming prisoners. When the commander of the town saw the reinforcements flee, he decided to abandon his post. He and his troops crossed over to the other side of the river, cut the pontoon bridge, and made their way back to Baghdad.[47]

With al-Anbar now lacking any defense, its residents decided to surrender on terms. After giving guarantees of safe conduct to the Anbaris, the Turks and North Africans entered the town, and allowed the people to go about their business. The next day, however, the soldiers seized a shipment of goods arriving from Raqqa and began looting the town. They sent the heads of the slain to Samarra, along with the prisoners that had been captured, and unsuccessfully attempted to dam a water route running between the Euphrates and Baghdad.[48]

When the defeated armies of al-Anbar arrived at Baghdad, Muhammad gave orders that the town was to be retaken. A contingent of troops was sent to Qasr ibn Hubayrah further down the Euphrates and awaited orders to advance. Meanwhile, an army of over a thousand men was raised in Baghdad and put under the command of al-Husayn b. Isma'il, who was instructed to head directly to the town and defeat the Samarran garrison stationed there. After a delay caused by an issue with the troops' pay, the army departed in late June.[49]

The Baghdadi army was assailed almost immediately after their departure by the Turks and North Africans, who attempted to prevent their reaching al-Anbar. In spite of stiff resistance, the Baghdadis were able to construct a bridge across a canal guarded by the Turks and fight them off, but after twelve days they had still failed to reach al-Anbar. Eventually the Turks, who had spies in the al-Husayn's army, were able to ambush their camp. Despite inflicting heavy casualties on the attackers, the Baghdadi army soon fell in disorder, and many of the soldiers were either killed or drowned in the Euphrates. The cavalry turned tail and fled, and when the officers realized that they had lost control of the situation they retreated as well. The Turks then plundered the enemy camp and rounded up the prisoners they had captured. Both sides suffered hundreds of dead and wounded from the fighting.[50]

The remnants of the defeated army retreated back to Baghdad, encamping in the city suburbs in the first week of July. Muhammad gave orders that al-Husayn was to be refused entry to Baghdad, and that any of al-Husayn's men that did not promptly leave the city for his camp would be flogged and denied pay. Al-Musta'in also sent a letter to the encamped soldiers, chastising them for their failure and accusing them of disobedience and mutiny. Al-Husayn was told to gather his men and make another effort to retake al-Anbar. By mid-July, al-Husayn's forces were ready, and for the second time they headed to retake the town.[51]

Al-Husayn's second campaign was to end as badly as the first. Once again the Turks defending the land between Baghdad and al-Anbar attacked the Baghdadi army. Al-Husayn was able to fight them off for several days, but eventually the Turks were able to outmaneuver him and rout the guards stationed on his flanks. When they attacked al-Husayn's army itself, they quickly defeated his men and overran his camp. Al-Husayn himself managed to escape on a river skiff, but a hundred of his men were killed and 170 had been taken prisoner, including several of the officers. Al-Husayn and the other survivors returned to Baghdad,[52] and there were no further attempts to retake al-Anbar.

Qasr ibn Hubayrah, the other western town garrisoned by Muhammad's forces, was taken by the Turks shortly after. Following the conquest of al-Anbar, the Samarran army headed to Qasr ibn Hubayrah and intended to expel the Baghdadis stationed there. Instead, its commander decided to flee the town, giving it up to the Turks without resisting.[53]

Al-Mada'in, to the south of Baghdad in the direction of Wasit, was a series of settlements lying in the midst of the ancient Persian imperial centers of Ctesiphon and Seleucia.[54] On April 21, on the orders of Muhammad b. 'Abdallah, Abu 'l-Saj Dewdad departed Baghdad for al-Mada'in at the head of three thousand cavalry and infantry units. He arrived in the area and settled his troops there. Later he wrote to Muhammad requesting reinforcements, which were sent to him.[55]

Over the course of the summer, the Turks began appearing in the vicinity of al-Mada'in in strength. Abu 'l-Saj responding by advancing further south, to the district of Jarjaraya, where in August he defeated a contingent of Turks and killed their commander.[56] In October he again fought the Turks near Jarjaraya and killed or captured a large number of them. Despite these victories, Abu 'l-Saj was reportedly unsatisfied with the performance of his troops during the fighting, and Muhammad arranged for more reinforcements to be sent to assist him. The reinforcements set out on October 23 and, after marching the entire day, arrived at al-Mada'in just as an army of Turks also appeared before the city.

Combat between the two sides began, but the defenders were quickly overwhelmed when the Turks found a breach in the city wall and forced their way through it. The defenders tried to implement an orderly retreat, with the infantry being loaded onto boats and moved along the river while the cavalry covered their withdrawal, but the Turks continued to engage them and the commander of the reinforcements died in the chaos. With al-Mada'in now lost to them, the survivors made their way to Abu 'l-Saj's camp. Muhammad was angered by the result of the battle, and ordered several of those who had fought at al-Mada'in to be placed under house arrest.[57]