The Abbasid caliphate as a sovereign institution ended at Baghdad on the 20th of February 1258 with the execution of al-Musta'sim. The institutional form of the caliphate — a religious-political office combining the temporal sovereignty of the Sunni Muslim community with formal religious authority over the Friday prayer, the legal-judicial system, and the public legitimating functions of state — continued, in various successor forms, for a further six hundred and sixty-six years until the formal abolition of the office by the Republic of Turkey on the 3rd of March 1924. The political-theological inheritance of the Abbasid institutional model continues, in altered forms, to shape Islamic political thought into the twenty-first century.
The Cairo shadow caliphate (1261–1517)
The Mamluk dynasty of Egypt — established at Cairo in 1250 by the dynastic succession of Turkish slave-soldier officers in the aftermath of the Ayyubid dynastic collapse — identified, in the years immediately after the Baghdad sack, an Abbasid family survivor whose transfer to Cairo would provide the legitimating authority that the new Mamluk political order required. The candidate, al-Mustansir (an uncle of the executed al-Musta'sim), arrived at Cairo in early 1261 and was proclaimed caliph in formal investiture by the Mamluk Sultan Baybars on the 13th of June 1261. The Cairo Abbasid line continued in unbroken succession for sixteen generations, from al-Mustansir (1261–1262) to al-Mutawakkil III (1508–1517).
The constitutional position of the Cairo Abbasid caliphs was restricted to the ceremonial. The political authority in Egypt was the Mamluk sultan; the caliphal role was confined to the formal investiture of new sultans, the conduct of the Friday sermon, the endorsement of legal-judicial matters of religious significance, and ceremonial appearances at state functions. The caliphal household was maintained by the Mamluk state at a allowance from the central treasury. The political legitimacy that the Abbasid presence conferred on the Mamluk state — recognition of the Mamluks as the legitimate Sunni political authority of the central Islamic territories — was the principal benefit of the arrangement to the Mamluks.
The Cairo caliphate ended with the Ottoman conquest of Mamluk Egypt in 1517. The Ottoman Sultan Selim I captured the last Cairo Abbasid caliph al-Mutawakkil III at the conquest of Cairo in August 1517, transferred him to Istanbul, and held him there until his death in 1543. The subsequent question of whether al-Mutawakkil III transferred the caliphate to Selim I — the basis of the subsequent Ottoman claim to the caliphate — is the source of subsequent historiographical argument.
The Ottoman claim
The Ottoman dynasty's claim to the caliphal title — articulated systematically from the late eighteenth century onward, but with earlier antecedents — rested on three principal arguments. First, the 1517 transfer (if it occurred) constituted a formal renunciation by the last Abbasid in favour of the Ottoman house. Second, the Ottoman conquest of the Hijaz (the holy cities of Mecca and Medina) in the same campaign conferred on the Ottoman sultan the Servant of the Two Holy Sanctuaries title — the principal honorific of Islamic political sovereignty. Third, the Ottoman dynasty's military and political defence of the Sunni Islamic world against the European Christian and Shia Persian rivals qualified the Ottoman sultan as the de facto religious-political leader of the worldwide Sunni community.
The systematic articulation of the Ottoman claim was deployed in the late eighteenth and nineteenth centuries — in the Treaty of Küçük Kaynarca of 1774, in which the Ottoman sultan recognised Russian sovereignty over Crimea on the condition that the sultan's religious authority over the Tatar Muslim population was recognised; and in the late-nineteenth-century pan-Islamic ideology of Sultan Abdul Hamid II (1876–1909), which deployed the caliphal claim as the basis for Ottoman political-religious authority over the Muslim populations of the European colonial empires (British India, Russian central Asia, Dutch east Indies, French north Africa).
The 1924 abolition
The Ottoman caliphate was terminated by the Republic of Turkey in two stages. The first stage, on the 1st of November 1922, was the abolition of the Ottoman sultanate (the political authority) by the Grand National Assembly under Mustafa Kemal — leaving the caliphate (the religious authority) as a separately held institution under the last Ottoman caliph Abdülmecid II (1922–1924). The second stage, on the 3rd of March 1924, was the abolition of the caliphate itself, the expulsion of Abdülmecid II and the Ottoman family from Turkey, and the formal end of the institution.
The 1924 abolition produced protest and alternative caliphal claims across the Sunni world. The Hashemite King Hussein of the Hejaz proclaimed himself caliph on the 5th of March 1924 — two days after the Turkish abolition — but the subsequent Saudi conquest of the Hejaz later in 1924 eliminated the claim. The Sharif of Mecca, Egyptian religious authorities, Indian Muslim political leaders all proposed alternative caliphal candidates; the 1926 Cairo Caliphate Conference attempted to organise a collective Sunni endorsement of a successor; the conference failed to produce a agreed candidate. The caliphate has remained vacant since 1924.
The legacy in Islamic political thought
The absence of a functioning caliphate has been the central question of Sunni Islamic political theology since 1924. The principal positions developed in the subsequent literature comprise: the reform-Islamic position (developed by Rashid Rida and subsequent scholars) that the caliphate is a necessary institution that must be restored, but only on the basis of authentic Islamic legal principles rather than the dynastic political arrangements of the historical caliphates; the secular-nationalist position (developed by 'Ali 'Abd al-Raziq in his 1925 Islam and the Foundations of Governance) that the caliphate was a historical political arrangement without religious authority and that the separation of religious and political institutions is the appropriate Islamic political position; and the Islamist position (developed by the Muslim Brotherhood, by Sayyid Qutb, by the subsequent Islamist movements) that the caliphate represents the true Islamic political form and that its restoration is the principal political objective of an authentic Islamic political programme.
The twenty-first-century attempt to restore the caliphate by the Islamic State of Iraq and Syria in 2014 — proclamation by Abu Bakr al-Baghdadi on the 29th of June 2014 of a new caliphate with territorial extent across portions of Iraq and Syria — was the first post-1924 attempt to actualise the restorationist position. The subsequent military destruction of the Islamic State by 2017–2019 produced the elimination of the particular project, but the broader question of the appropriate Islamic political form remains the central question of contemporary Sunni political theology.
The cultural-intellectual inheritance of the Abbasid period — the Greek-to-Arabic translation movement, the development of Sunni legal-theological traditions, the flowering of poetry and literature, the scientific and philosophical achievement — continues to shape the cultural identity of the contemporary Islamic world. Baghdad itself, destroyed by the Mongols in 1258 and subsequently rebuilt under Ottoman and modern Iraqi sovereignty, remains the capital of the Iraqi state and preserves residual physical evidence of its early-medieval grandeur. The Round City itself disappeared with the 813 siege; the Bayt al-Hikma disappeared with the 1258 sack; the caliphal palaces disappeared with the subsequent destructions; but the city, the language, the religious tradition, and the broader cultural inheritance continue.
End of Chapter X