Al-Ma'mun al-Bata'ihi

12th-century Fatimid vizier Abu Abdallah Muhammad ibn Fatak , better known as al-Ma'mun al-Bata'ihi ( Arabic : المأمون البطائحي ), was a senior official of the Fatimid Caliphate in the early 12th century, during the reign of al-Amir . His origin is obscure, but his father had held high military office, and thus al-Bata'ihi belonged to the Fatimid Egyptian elite. In 1107, at the age of about 21, he was chosen as chief of staff of the vizier al-Afdal Shahanshah , the de facto ruler of the state. In this capacity al-Bata'ihi carried out tax reforms which raised revenue and ensured the payment of the military . Al-Afdal was assassinated in 1121, officially by agents of the rival Nizari branch of Isma'ilism , which opposed the official Fatimid Musta'li Isma'ilism and did not recognize al-Amir as caliph and imam . However, both Caliph al-Amir and al-Bata'ihi are suspected to have been involved in the murder by some sources. Al-Amir appointed al-Bata'ihi to the vacant vizierate, establishing a partnership between caliph and vizier that brought the former once again into the public view, while retaining for the latter the de facto governance of the state. As vizier, al-Bata'ihi was noted for his ability, justice, and generosity. He celebrated lavish festivals, where al-Amir had the opportunity to play a central role, and commissioned several buildings, of which the most important and only surviving one is the Aqmar Mosque in Cairo . Al-Bata'ihi also hunted down Nizari agents and sympathizers; the al-Hidaya al-Amiriyya , issued in 1122, rebuffed Nizari claims and affirmed the legitimacy of Musta'li Isma'ilism. During his tenure, the Fatimids became more directly involved in Yemen , often ignoring their Sulayhid ally, Queen Arwa . In the Levant , attempts to take the offensive against the Crusaders failed, with a naval defeat at the hands of the Venetian Crusade in 1123 followed by the loss of Tyre in 1124. These failures, coupled with the caliph's resentment at al-Bata'ihi's power, led to his dismissal and imprisonment by al-Amir in 1125. He was then kept imprisoned until July 1128, when al-Amir ordered his execution. His son, Musa , wrote a biography that survives in fragments and is a key source for al-Bata'ihi's career.