Some scholars identify him with "Abu Muhammad al-Hasan ibn Ali", also known as Ibn Ammar, a leader of the KutamaBerbers and chief minister (wāsiṭa) during the first year of the reign of the Fatimid Caliph al-Hakim bi-Amr Allah (r. 996–1021), but this is disputed.
Following the Byzantine reconquest of Crete in 960–961, the Fatimids once more turned their attention to Sicily, where they decided to reduce the remaining Byzantine outposts in the northeast and complete the Muslim conquest of the island. On Christmas Day 962 Hasan and his cousin AhmadcapturedTaormina after a siege of seven and a half months, while on 24 August 963 Hasan laid siege to Rometta. The garrison of the latter sent for aid to Emperor Nikephoros II Phokas. The Emperor prepared a major expedition, allegedly 40,000 strong, which arrived in Italy in late 964. Learning of this, Hasan also sought reinforcements, which arrived under the command of his namesake uncle. The Byzantines attempted to relieve Rometta, and on 25 October 964 clashed with Hasan's army. The Byzantines were victorious in the initial engagement, but Hasan managed to rally his men and won a crushing victory. According to al-Maqrizi and Abu'l-Fida, more than 10,000 Byzantines fell, including the Emperor's nephew, Manuel Phokas, and several other commanders. The surviving Byzantines fled in panic, but were badly mauled again when the Arabs caught up with them in a defile ("battle of the pit", waqʿat al-ḥufra). The remnants of the Byzantine troops boarded their ships, but the Byzantine fleet was destroyed at the Battle of the Straits by Hasan's cousin Ahmad, sealing the fate of Rometta. The city surrendered a few months later, in early 965, after its provisions were exhausted and its inhabitants started fleeing the city.[3][5]
Disputed identity
Michael Brett and other scholars identify al-Hasan al-Kalbi with another Ibn Ammar, who in 971 led an army of Kutama Berbers to reinforce the Fatimid troops in Egypt, and who after the death of Caliph al-Aziz Billah (r. 975–996) became briefly regent with the title of wāsiṭa ("intermediary"), and led a staunchly pro-Berber regime that antagonized the other factions of the army, until he was overthrown by Barjawan in October 997.[6][7][8] Other scholars consider the later Ibn Ammar to have himself been a Kutama Berber leader, under the name of "Abu Muhammad al-Hasan ibn Ali".[9][10][11][12]
Bianquis, Thierry (1972). "La prise de pouvoir par les Fatimides en Égypte (357‑363/968‑974)" [The Seizure of Power by the Fatimids in Egypt (357–363/968–974)]. Annales Islamologiques (in French). XI: 49–108. doi:10.3406/anisl.1972.950. S2CID259055451.
Halm, Heinz (2003). Die Kalifen von Kairo: Die Fatimiden in Ägypten, 973-1074 [The Caliphs of Cairo: The Fatimids in Egypt, 973-1074] (in German). Munich: C. H. Beck. ISBN3-406-48654-1.