The second Syria campaign of Ali refers to the abortive efforts of Ali ibn Abi Talib, the Muslim caliph () and the first Shia Imam, to organize a renewed military campaign against Mu'awiya, the rebellious governor of Syria. Following the indecisive Battle of Siffin against Mu'awiya in 657 CE, Ali subdued the Kharijites revolt in the Battle of Nahrawan in 658, but his military coalition in Iraq collapsed afterward when the tribal chiefs withdrew their support, as they hoped for peace with Mu'awiya on beneficial terms. Ali henceforth could barely muster enough force to repel the frequent raiding parties dispatched by Mu'awiya to harass the civilian population loyal to Ali. Egypt too fell to Mu'awiya in 658, further limiting the influence of Ali outside of Iraq. Following the raid of Busr ibn Abi Artat in 661, however, the public outrage against Mu'awiya finally seems to have galvanized the Iraqis' support for war, and a large offensive was planned for the late winter. These plans were abandoned after the assassination of Ali by the Kharijite Ibn Muljam on 26 January 661, during the morning prayers. His assassination paved the way for Mu'awiya, who later founded the Umayyad Caliphate.

Background 
The controversial policies of the third caliph Uthman resulted in a rebellion that led to his assassination in 656 CE. Ali ibn Abi Talib, the son-in-law and cousin of the Islamic prophet Muhammad, was subsequently elected caliph by the Medinans and the dissidents present there. There he received a nearly unanimous pledge of allegiance, gathering various underprivileged groups around himself. His broad coalition consisted of the Medinan Muslims, known as the Ansar, the Iraqi  (), who were the earlyc settlers of Iraq, and finally the late-comers to Iraq, who were led by their influential tribal elite. In contrast, Ali found limited support among the powerful Quraysh tribe, some of whom aspired to the title of caliph. Among the Quraysh, the caliphate of Ali was soon challenged by Aisha, a widow of Muhammad, and two of his companions, namely, Talha ibn Ubayd Allah and Zubayr ibn al-Awwam. Uthman's cousin Mu'awiya also denounced the accession of Ali when he was dismissed from his post as the governor of Syria. He now demanded retribution against Uthman's killers. 

Ali defeated the rebellion of Aisha, Talha, and Zubayr in the Battle of the Camel in 656, but the Battle of Siffin against Mu'awiya in 657 resulted in a stalemate when the latter called for arbitration by the Quran to avoid defeat. The strong peace sentiments in Ali's army compelled him to accept the offer, and an ill-fated arbitration committee was set up with representatives from Ali and Mu'awiya with a mandate to settle the dispute in the spirit of the Quran. As Ali marched back to Kufa, his capital, a group of his soldiers criticized the arbitration and accused Ali of blasphemy for leaving the matter to the discretion of two men. Most of them had earlier forced Ali to accept the arbitration but now exclaimed that the right to judgment belonged to God alone. Many of them were won back by Ali, while the rest assembled near the Nahrawan Canal on the east bank of the Tigris river. Following this exodus, they became known as Khawarij (). The Kharijites denounced Ali as caliph, declared him, his followers, and the Syrians as infidels. They declared the blood of such infidels to be licit, and committed many murders, apparently not even sparing women. Ali crushed them in the Battle of Nahrawan in 658, but their remnants and offshoots continued to terrorize for many years.

Aftermath of the Battle of Nahrawan 

After the Battle of Nahrawan, Ali wanted to immediately resume his campaign against Mu'awiya, but this was protested by al-Ash'ath ibn Qays, an influential Yemenite tribal leader, who complained that the troops were exhausted and urged Ali to return to Kufa to recuperate. Exhaustion was possibly a pretext for Ibn Qays and the other tribal leaders () who wanted to avoid another war with Mu'awiya, or perhaps their request simply echoed the troops' sentiments. In any case, Ali yielded and returned to Kufa, where he camped at al-Nukhayla, just outside the city, and ordered his men to prepare for war and only occasionally visit their families in Kufa. Ali then sent his son Hasan to Kufa to rally support and draft new fighters, but he was met with little success there and even the troops at al-Nukhayla deserted the camp and returned to Kufa in the coming days. Ali was thus compelled to abandon his plans and returned to Kufa. 

Among modern historians, Fred Donner suggests that the killing of pious Muslims in the Battle of Nahrawan damaged the moral claim of Ali to leadership because, in his view, the Kharijites were the best representatives of Islam, albeit less flexible than Muhammad. For Donner, this and the fact that Syrian and Iraqi troops belonged to the same tribes explains the reluctance of the Iraqis for another battle with the Syrians. In contrast, M.A. Shaban believes that the tribal leaders had just quashed their  rivals in the Battle of Nahrawan and were now reluctant to again fight the Syrians, with whom they hoped to make peace. Indeed, the  and the tribal leaders vied for political power based on their Islamic credentials and tribal pedigree, respectively. Similarly, the opinion of Husain M. Jafri () is that the tribal leaders stood to lose their Uthman-era status because Ali probably intended to restore the Islamic leadership in Kufa at the cost of its tribal aristocracy. After the Battle of Siffin, the tribal leaders urged Ali to address the threat of the Kharijites, whose ranks were filled with the . When the Kharijites were defeated, the tribal leaders rejected Ali's call for a renewed campaign against Mu'awiya, who had secretly offered them status and wealth in return for their support. By contrast, Ali refused to grant any financial favors to the tribal chiefs as a matter of principle. So they abandoned Ali on "lame excuses," writes Jafri. At any rate, the secession of so many of the  and the coolness of the tribal leaders weakened the coalition of Ali.

Fall of Egypt 
Around this time, Mu'awiya dispatched an army of some 6,000 men to Egypt under the command of Amr ibn al-As, who had earlier conquered the region during the caliphate of Umar (). As he entered Egypt, Amr was joined by the local supporters of Uthman. Muhammad ibn Abi Bakr, the governor of Ali and his foster son, marched to meet Amr with a much smaller army of about 2,000 men, but they abandoned him when his vanguard, led by Kinana ibn Bishr, was crushed by Amr. Nearly dead from thirst, Muhammad was caught, refused water, and then killed. His corpse was set on fire inside the carcass of a donkey. Egypt thus fell in August 658 (Safar 38 AH). Before his defeat, Muhammad ibn Abi Bakr had asked Ali for reinforcements but the caliph could only muster some 2,000 men even after reproaching the tribal chiefs for their inaction. This was already too late and the force was disbanded when Ali learned about the fall of Egypt. The death of his foster-son deeply saddened Ali, who wrote to his confidant Ibn Abbas and bitterly complained about the Kufans' inaction. In his letter, he praised Muhammad ibn Abi Bakr for fulfilling his duty but also admitted that he was young and inexperienced. The far more capable Malik al-Ashtar was killed by poison in 657 at the instigation of Mu'awiya en route to Egypt to replace Muhammad.

Syrians' raids 

Mu'awiya also began to dispatch military detachments to harass the civilian population loyal to Ali. These units evaded enemy forces and instead targeted civilians in the areas along the Euphrates, the vicinity of Kufa, and most successfully, Hejaz and Yemen. Ali could not mount a timely response to these assaults. In the case of the raid led by Busr ibn Abi Artat in 661, the Kufans eventually responded to calls for jihad and routed Muawiya's force, but only after the enemy had reached Yemen. There are allegations of atrocious crimes committed by Busr, including the murder of the two minor sons of Ubayd Allah ibn Abbas, a relative of Ali, and enslaving Muslim women, apparently for the first time. The raids were likely intended to undermine Ali's efforts for a renewed Syria campaign.

Iran 
The final years of the caliphate of Ali also witnessed a number of revolts in the eastern provinces, taking advantage of the weakened central government. In the eastern province of Khorasan, the city of Nishapur was at one point occupied by the rebels and the province likely saw one or two rebellions during this period. Around 660, the governors of Fars and Kirman were expelled and Ali sent Ziyad ibn Abih, who restored order there. The early sources are reticent about these developments as they focus on Iraq instead.

Second Syria campaign 
In his final months, Ali repeatedly complained about the perpetual disobedience of the Kufans in the public sermons attributed to him in . He nevertheless continued his efforts to mount a second Syrian campaign and appears to have finally found sufficient support for an offensive, set to commence in late winter 661. This was in part due to the public outrage in the wake of the infamous Syrian raid led by Busr in 661. Following the raid, a group of Kufan tribal chiefs pledged their support for war and enlisted their men, while Ali separately recruited new fighters from the Sawad region. By one account, Ali thus gathered some 40,000 men, eager to march on Syria. In preparation for war, a party was dispatched to raid Syria under the command of Ziyad ibn Khasafa, but it is unlikely to have inflicted substantial damage since Ali had ordered the unit to fight only those who would fight them and to avoid wronging anyone or interfering with the bedouins. The planned second campaign was nevertheless abandoned after the assassination of Ali on 26 January 661 by the Kharijite Ibn Muljam. His assassination paved the way for Mu'awiya, who later founded the Umayyad Caliphate.

Footnotes

References 

 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 

Military history of the Rashidun Caliphate