His reign saw the capture of Damascus and the Fatimid expansion into the Levant, which brought al-Aziz into conflict with the Byzantine emperor Basil II over control of Aleppo.

During the course of this expansion, al-Aziz took into his service large numbers of Turkic and Daylamite slave-soldiers, thereby breaking the near-monopoly on Fatimid military power held until then by the Kutama Berbers.

[1] According to the sources, al-Aziz Billah was "tall, with red hair and blue eyes, generous, brave, fond of horses and hunting and very humane and tolerant in disposition".

[1] He was marked for his skill as an administrator, reforming the finances of the Fatimid state, standardizing and streamlining the payment of officials, and taking steps to ensure their integrity.

[1] At the same time, he was known for his extravagant lifestyle and obsession for precious objects and materials, rare animals and delicacies; it is said that on one occasion, he had carrier pigeons bring him cherries from Ba'albek.

[9] Ibn Killis is credited with the capable administration of the public finances, which ensured a full treasury despite the vast sums expended by the luxury-loving Caliph,[10] but also for his role as a patron of men of letters, and the author of a book that codified Fatimid laws.

Berbers, and especially the Kutama tribe, were traditionally the mainstay of the Fatimid armies, and had played the main role in the takeover of Ifriqiya and the conquest of Egypt and the southern Levant under al-Aziz's predecessors.

[12][13] However, the forays into the Levant revealed the inadequacies of an army based mostly on the Kutama, and from 978, al-Aziz began to introduce mercenaries from the Islamic East, especially Turkic and Daylamite slave-soldiers (ghilmān).

[1] This leniency, crowned by the appointment to high office of Ibn Nesturus and Manashsha, was resented by the Muslim populace, incensed by hostile tracts circulating among them.

[1] This tolerance did not extend towards the Sunni Muslim population, however, as al-Aziz followed a fervently Isma'ili agenda: he erected inscriptions denouncing the Companions of the Prophet, abolished the Tarawih prayers in 982, and initiated the celebration of the Ashura festival in Cairo.

[20][21] Possession of Syria, and particularly Palestine, was a constant foreign policy objective for many rulers of Egypt both before and after the Fatimids, to foreclose the most likely invasion route into the country by the empires of Western Asia.

[9][23] At the same time, the balance of power in the region was altered with the simultaneous expansion of the Byzantine Empire into northern Syria against the Hamdanid Emirate of Aleppo, culminating in the capture of Antioch in 969.

[23] Despite initial successes, the first Fatimid invasion of Syria, under the Kutama general Ja'far ibn Fallah, quickly came to a halt through a combination of rebellions by the citizens of Damascus and the Bedouin tribes of the Syrian Desert.

[30] In 976, the Fatimid general Jawhar, the conqueror of Egypt, campaigned against Damascus, but after two months of clashes before the city he had to retreat due to the arrival of Alptakin's Qarmatian allies.

[9] Nevertheless, as noted before, this event was of momentous importance and marked a major departure from previous Fatimid practice; especially in Syria, the Turkish ghilmān remained influential and men from their ranks often occupied the position of governor of Damascus.

[15] Damascus itself was taken over by one of Alptakin's lieutenants, Qassam, with the support of the local population and the city militia (aḥdāth), who wished to avoid a renewed Berber occupation.

[9][33] Matters became complicated with the arrival of Abu Taghlib, the ousted Hamdanid ruler of Mosul, who contacted al-Aziz with an offer to capture the city if they supported him with troops.

[9][33] At the same time, despite al-Fadl's efforts to use the Uqayl to contain them, the Tayy and their unchecked depredations grew to be a menace to the settled and agricultural districts of southern Syria: Ramla was "reduced to a ghost town", in the words of Kennedy, and the Ghouta plain around Damascus and the Hawran region were so devastated that Damascus faced famine, alleviated only through supplies sent from Homs, ruled by the Turk Bakjur for the Hamdanids of Aleppo.

Baltakin defeated Ibn al-Jarrah, who fled north to Antioch and the protection of the Byzantines, while Qassam was finally forced to surrender Damascus in early 983, albeit under generous terms that allowed him to remain in control under a Fatimid-appointed governor.

[9][33] After securing Fatimid rule in central and southern Syria, Caliph al-Aziz aimed to capture Aleppo as well, but was restrained by Ibn Killis while he lived.

Sa'd al-Dawla was forced to appeal to the Byzantine emperor Basil II (r. 976–1025) for help, who sent his general Bardas Phokas the Younger to assist Aleppo.

[9][13] At the same time, Baltakin was sent to pacify the Bedouin tribes who were raiding the Hajj caravans, leading to the establishment of a Fatimid garrison at Wadi al-Qura, north of Medina.

[42] Manjutakin invaded the Hamdanid emirate, defeated a Byzantine force under the doux of Antioch, Michael Bourtzes, in June 992, and laid siege to Aleppo.

However, he failed to pursue the siege with vigour and the city was easily able to resist until, in the spring of 993, after thirteen months of campaigning, Manjutakin was forced to return to Damascus due to lack of supplies.

The blockade was far more effective this time and soon caused a severe lack of food, but the city's defenders held out until the sudden arrival of the Byzantine emperor, Basil II, in person in April 995.

[46] Manjutakin was ordered to recapture Tartus, but its Armenian garrison was able to fend off his attacks; and a Fatimid fleet sent to assist the siege was lost in a storm off the coast.

[49] According to Kennedy, these diplomatic victories were the result of the more energetic foreign policy pursued by al-Aziz, particularly after the death of Ibn Killis, which bolstered his credentials by demonstrating "his ability and willingness to undertake the two major public responsibilities of a caliph, to safeguard the Hajj and to lead the Muslims against the infidel Byzantines".