Some scholars identify him with "Abu Muhammad al-Hasan ibn Ali", also known as Ibn Ammar, a leader of the Kutama Berbers 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.
Along with Ahmad, Ammar fought in the wars with the Byzantine Empire in Sicily and southern Italy, and drowned during an abortive expedition against Otranto in 958.
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).
[3][5] 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.