After Yazid died in November 683, the Mecca-based rebel Abd Allah ibn al-Zubayr declared himself caliph and expelled Marwan, who took refuge in Syria, the center of Umayyad rule.

The tribal nobility, led by Ibn Bahdal of the Banu Kalb, elected Marwan and together they defeated the pro-Zubayrid Qays tribes at the Battle of Marj Rahit in August of that year.

In the months that followed, Marwan reasserted Umayyad rule over Egypt, Palestine, and northern Syria, whose governors had defected to Ibn al-Zubayr's cause, while keeping the Qays in check in the Jazira (Upper Mesopotamia).

Although Marwan was stigmatized as an outlaw and a father of tyrants in later anti-Umayyad tradition, the historian Clifford E. Bosworth asserts that the caliph was a shrewd, capable, and decisive military leader and statesman who laid the foundations of continued Umayyad rule for a further sixty-five years.

[2] His father was al-Hakam ibn Abi al-As of the Banu Umayya (Umayyads), the strongest clan of the Quraysh, a polytheistic tribe which dominated the town of Mecca in the Hejaz.

[2] Marwan's mother was Amina bint Alqama of the Kinana,[2] the ancestral tribe of the Quraysh which dominated the area stretching southwest from Mecca to the Tihama coastline.

[11] During the reign of Caliph Uthman (r. 644–656), Marwan took part in a military campaign against the Byzantines of the Exarchate of Carthage (in central North Africa), where he acquired significant war spoils.

At an undetermined point, he served as Uthman's governor in Fars (southwestern Iran) before becoming the caliph's katib (secretary or scribe) and possibly the overseer of Medina's treasury.

[14] According to the traditional Muslim reports, many of Uthman's erstwhile backers among the Quraysh gradually withdrew their support as a result of Marwan's pervasive influence, which they blamed for the caliph's controversial decisions.

"[13] Discontent over Uthman's nepotistic policies and confiscation of the former Sasanian crown lands in Iraq[a] drove the Quraysh and the dispossessed elites of Kufa and Egypt to oppose the caliph.

[2][13][23] According to tradition, he was saved by the intervention of his wet nurse, Fatima bint Aws, and was transported to the safety of her home by his mawla (freedman or client), Abu Hafs al-Yamani.

[31] Marwan was present alongside Mu'awiya at the Battle of Siffin near Raqqa in 657,[32] which ended in a stalemate with Ali's army and abortive arbitration talks to settle the civil war.

[11] Bosworth speculates that it "may have been fears of the family of Abu'l-ʿĀs that impelled Muʿāwiya to his adoption of his putative half-brother Ziyād b. Sumayya [Ziyad ibn Abihi] and to the unusual step of naming his own son Yazīd as heir to the caliphate during his own lifetime".

[51] Al-Walid accepted, prompting Marwan, who attended the meeting, to castigate the governor and demand Husayn's detention until he proffered the oath of allegiance to Yazid or his execution should he refuse.

[54] Meanwhile, Ibn al-Zubayr avoided al-Walid's summons and escaped to Mecca, where he rallied opposition to Yazid from his headquarters in the Ka'aba, Islam's holiest sanctuary where violence was traditionally banned.

[54] In 683, the people of Medina rebelled against the caliph and assaulted the local Umayyads and their supporters, prompting them to take refuge in Marwan's houses in the city's suburbs where they were besieged.

[57][58] In response to Marwan's plea for assistance,[57] Yazid dispatched an expeditionary force of Syrian tribesmen led by Muslim ibn Uqba to assert Umayyad authority over the region.

[11] In the ensuing Battle of al-Harra in August 683, Marwan led his horsemen through Medina and launched a rear assault against the Medinese defenders fighting Ibn Uqba in the city's eastern outskirts.

[11] However, he was encouraged by the expelled governor of Iraq, Ubayd Allah ibn Ziyad, to volunteer himself as Mu'awiya II's successor during a summit of loyalist Syrian Arab tribes being held in Jabiya.

[62] The general recognition of Ibn al-Zubayr adhered to the Islamic principle of passing leadership to the most righteous and eminent Muslim,[62] while the Umayyad loyalists at the Jabiya summit debated the two other principles: direct hereditary succession as introduced by Mu'awiya I and represented by the nomination of his adolescent grandson Khalid ibn Yazid; and the Arab tribal norm of selecting the wisest and most capable member of a tribe's leading clan, epitomized in this case by Marwan.

[63] The organizer of the Jabiya summit, Ibn Bahdal, the chieftain of the powerful Banu Kalb tribe and maternal cousin of Yazid,[49] supported Khalid's nomination.

[72] The remnants of Qays rallied around Zufar ibn al-Harith al-Kilabi, who took over the fortress of Qarqisiya (Circesium) in Upper Mesopotamia, from which he led the tribal opposition to the Umayyads.

[14] In a poem attributed to him, Marwan thanked the Yamani tribes for their support at Marj Rahit: When I saw that the affair would be one of plunder, I made ready Ghassan and Kalb against them [the Qays],And the Saksakīs [Kindites], men who would triumph, and Ṭayyi', who would insist on the striking of blows,And the Qayn who would come weighed down with arms, and of Tanūkh a difficult and lofty peak.

[74] Marwan appointed the Ghassanid Yahya ibn Qays as the head of his shurta (security forces) and his own mawla Abu Sahl al-Aswad as his hajib (chamberlain).

[72] By early 685, he dispatched an army led by Ibn Ziyad to conquer Iraq from the Zubayrids and the pro-Alids[11] (partisans of Caliph Ali and his household and the forerunners of the Shia sect of Islam).

[11] Although it is widely reported in the traditional Muslim sources that Marwan was killed in his sleep by Umm Hashim Fakhita in retaliation for a serious verbal insult to her honor by the caliph, most western historians dismiss the story.

[81] By making his family the foundation of his power, Marwan modeled his administration on that of Caliph Uthman, who extensively relied on his kinsmen, as opposed to Mu'awiya I, who largely kept them at arm's length.

[70][82] In the view of Bosworth, Marwan "was obviously a military leader and statesman of great skill and decisiveness amply endowed with the qualities of ḥilm [levelheadedness] and shrewdness, which characterised other outstanding members of the Umayyad clan".

[11] His rise as caliph in Syria, a largely unfamiliar territory where he lacked a power-base, laid the foundations for Abd al-Malik's reign, which consolidated Umayyad rule for a further sixty-five years.

[86] Donner notes the difficulty of "achieving a sound assessment of Marwan", as with most Islamic leaders of his generation, due to an absence of archaeological and epigraphic documentation and the restriction of his biographical information to often polemical literary sources.