Abu al-Hajjaj Yusuf ibn Ismail (Arabic: أبو الحجاج يوسف بن إسماعيل; 29 June 1318 – 19 October 1354), known by the regnal name al-Muayyad billah (المؤيد بالله, "He who is aided by God"),[1] was the seventh Nasrid ruler of the Emirate of Granada on the Iberian Peninsula.

After gaining more control of the government, in 1338 or 1340 he expelled the Banu Abi al-Ula family, who had masterminded the murder of his brother and had been the leaders of the Volunteers of the Faith—North African soldiers who fought for Granada.

Abu al-Hajjaj Yusuf ibn Ismail was born on 29 June 1318 (28 Rabi al-Thani 718 AH) in the Alhambra, the fortified royal palace complex of the Nasrid dynasty of the Emirate of Granada.

She was an umm walad (freed concubine) originally from the Christian lands, described as "noble in good deeds, chastity and equanimity" by Yusuf's vizier, the historian Ibn al-Khatib.

[4] Ibn al-Khatib described the young Yusuf as "white-skinned, naturally strong, had a fine figure and an even finer character", with large eyes, dark straight hair and a thick beard.

[7] Through a combination of diplomatic and military manoeuvres, the emirate succeeded in maintaining its independence, despite being located between two larger neighbours: the Christian Crown of Castile to the north and the Muslim Marinid Sultanate across the sea in Morocco.

[10] Yusuf's predecessor, Muhammad IV, sought help from the Marinid Sultanate to counter a threat by an alliance of Castile and the powerful Granadan commander Uthman ibn Abi al-Ula, who supported a pretender to the throne in a civil war.

Subsequently, the Marinid–Granadan forces captured Gibraltar and fended off a Castilian attempt to retake it, before signing a peace treaty with Alfonso XI of Castile and Abu al-Hasan Ali of the Marinids the day before Muhammad IV's assassination.

They were the sons of Uthman ibn Abi al-Ula, who died in 1330, and his successors as the leaders of the Volunteers of the Faith, the corps of North Africans fighting on the Iberian Peninsula for Granada.

[2] Another modern historian, Francisco Vidal Castro, writes that the declaration and the oath of allegiance took place in the Muslim camp near Gibraltar instead of in the capital, and that the instigators of the assassination, the Banu Abi al-Ula brothers, were the ones who proclaimed him.

[2] Coming to the throne at the age of fifteen, Yusuf was initially treated as a minor and, according to Ibn al-Khatib, his authority was limited to only "choosing the food to eat from his table".

[17] The peace that Muhammad IV secured after the siege of Gibraltar was, by the principles of the time, rendered void by his death, and representatives of Yusuf met with those of Alfonso XI and Abu al-Hasan Ali.

[20] With the treaty in place, the monarchs redirected their attentions elsewhere: Alfonso XI cracked down on his rebellious nobles, while Abu al-Hasan waged war against the Zayyanid Kingdom of Tlemcen in North Africa.

[22][b] The personal rivalry between Martínez and de Guzmán appears to have caused the former to defect to Yusuf, but he was soon captured by Castilian forces, hanged as a traitor and his body burned.

[29] The Muslim strength is unclear: contemporary Christian sources claimed an exaggerated 53,000 horsemen and 600,000 foot soldiers,[31] while modern historian Ambrosio Huici Miranda in 1956 estimated 7,000 Granadan troops and 60,000 Moroccans.

[33] Various Muslim authors laid the blame on the Marinid Sultan, with Umar II of Tlemcen saying that he "humiliated the head of Islam and filled the idolaters with joy",[32] and al-Maqqari commenting that he allowed his army to be "scattered like dust before the wind".

In response, Yusuf moved to a strong position in Pinos Puente to block Castilian attempts to raid further into the rich plains surrounding the city of Granada.

[36] In May 1342, a Marinid–Granadan fleet sailing in the Strait of Gibraltar was ambushed by Castilian and Genoese ships, resulting in a Christian victory, the destruction of twelve galleys and the dispersal of other vessels along the Granadan coast.

[45][49] He sent an envoy, named Hasan Algarrafa in Castilian chronicles, and offered the surrender of Algeciras if its inhabitants were allowed to leave with their movable property, in exchange for a fifteen-year peace between Granada, Castile and the Marinids.

Peter, seeking to incite another civil war in North Africa, provided ships to land the prince in Sus in order to attack Abu Inan.

[56] The "preeminent writer and intellectual of fourteenth-century al-Andalus" according to Catlos,[75] throughout his lifetime Ibn al-Khatib produced works in subjects as diverse as history, poetry, medicine, manners, mysticism and philosophy.

On solemn state occasions, Yusuf presided over court activities from a wooden folding armchair that is currently preserved in the Museum of the Alhambra and bears the Nasrid coat of arms across its back.

[2] Ibn al-Khatib describes other anecdotes that illustrate Yusuf's popularity, including his reception by a well-respected judge in Purchena, by the people—including common womenfolk—of Guadix in 1354 and by certain Christian merchants in the same year.

[83] He was known for his strong opinions; in one occasion, he wrote a poem to Yusuf warning him of officials who squandered tax revenues, and in another, he reminded the Sultan of his responsibilities to his subjects as a Muslim leader.

[85] Yusuf strengthened the function of the muftis, distinguished jurists who issued legal opinions (fatwas), often to assist judges in interpreting difficult points of Islamic law.

[79] On the other hand, Yusuf had a mystical inclination that displeased the jurists (fuqaha) in his court, including his appreciation of the famous philosopher al-Ghazali (1058–1111), whose Sufi doctrines were disliked by the mainstream scholars.

Apart from their wedding in 738 AH (c. 1338 CE), there is no reference to this wife in the historical sources, leading the historian Bárbara Boloix Gallardo to speculate that she might have died early.

[96] Yusuf's concubine Maryam/Rim played an important role after his death: In 1359, she financed a coup that involved 100 men and deposed her stepson Muhammad V in favour of her son Ismail.

[102] Vidal Castro considers it unlikely that the attacker planned a political plot of his own, given his mental condition, or that the instigators aimed to have a demented bastard enthroned, given that Yusuf had his own sons as heirs.

However, Harvey notes that he was defeated at Río Salado, "the greatest single reverse suffered by the Muslim cause" during the Nasrid period before the fall of Granada, and presided over the strategically significant losses of Algeciras and Alcalá de Benzaide.