TLDR Imamat History: Egypt
Aby Tamim bin alMansoor alMuiz liDinAllah was thoroughly trained in both Ismaili doctrine and the fine arts. He studied law and learned seven languages. When he became Imam/Caliph, he made sure his soldiers were also educated in the religion, as well as arts and culture. Just like his father and grandfather, he had his sights set on Egypt. alMuiz spent two years building roads and infrastructure between Mahdia and Egypt in order to support troops travelling across North Africa. He placed Jawhar, from Sicily, in charge of the invasion. Jawhar peacefully conquered Alexandria and then, after some resistance, Fustat. He then built a new Fatimid capital just outside of Fustat called alQahira, or Cairo, after the planet Mars (alQahir). alMuiz had planned out the capital city before sending Jawhar to conquer the land and build it. It featured large public squares, multiple palaces, and mosques. Egypt was left in shambles after being conquered, so Jawhar set up institutions to quell uprisings and redistribute food to the people. As alMuiz made his way to Cairo, he quelled uprisings and installed satellite governments along the way to maintain peace across North Africa. Once in Cairo, alMuiz started having a hands-on approach to the Ismaili Mission. Instead of relying on disparate Dais to convey messages, alMuiz worked directly with Dai Jafar (alYemeni's son) and Qadi Numan to organize the network of Dais and compile legal and historical literature, respectively. With this new organized structure, the Mission soon spread to India. With Egypt finally in his control, alMuiz shifted the focus of his empire from conquering to learning. He personally funded public libraries in Mansuriya, Tunisia, and Cairo, and encouraged all people to partake in literature from across the Arab world and Europe, even going so far as to pay scribes to translate texts into Arabic for easy-reading. He also encouraged celebrations on secular holidays (such as Navroz) in addition to Muslim Eids and the birthdays of the Prophet's family members.
Abu Mansoor Nizar alAziz Billah continued his father's work, presiding over the intellectual epicenter Cairo and quelling the occasional uprising. One governor in North Africa, Bulkin (and after his death, his son Mansoor) constantly started revolts with the Zanata tribe. alAziz sent a Dai to suppress another uprising, but the Dai was killed and Mansoor remained in power until he died (at the same time as alAziz). Back in Cairo, alAziz appointed Yaqub ibn Killis, his father's financial officer, to the position of Chief Vizier, where he directed foreign trade and standardized Fatimid currency. alAziz also built a library inside the alAzhar Mosque and converted it into a university. alAziz died of illness on his way to Syria, to meet with the Byzantines.
Imam alHakim biAmrillah
alHakim biAmrillah became the Imam/Caliph at the age of 11. At his father's request, he was advised by treasurer Barjuwani, Qadi Muhammad (Qadi Numan's son), and Amir Hassan bin Ammar. On the empire's borders, Barjuwani was in charge of the Turkish guards and Ibn Ammar controlled the Berber guards. The two groups clashed and both men were killed. At the age of fifteen, alHakim took control of the Fatimid Empire on his own; he appointed Jawhar's son, Husayn, as his vizier. alHakim would ride through the streets of Cairo in order to see how his people lived, as well as listen to their complaints. As a result, he cracked down on certain trades and enforced Ismaili laws on produce, fish, and alcohol, as well as mandating Ismaili prayers. Christian, Jewish, and Sunni citizens had gotten used to Imam alAziz's leniency and plurality and didn't approve of alHakim's Ismaili-centric laws, and when alHakim began conducting expensive and secretive science experiments, people became suspicious. Abu Rakwa, an Umayyad prince who had joined the Zanata, teamed up with Banu Qurra, who sympathised with the Khwarij, to invade Cairo, but alHakim sent his own army to meet them in Alexandria. alHakim's army followed Abu Rakwa south, with each army on different sides of the river Nile, and Abu Rakwa was quickly defeated north of the city. Even though this revolt was unsuccessful, its combination with the Nile failing to rise that year plunged Cairo into famine and bankruptcy. This caused alHakim to lift all restrictions for non-Ismaili citizens: Sunnis, Christians, and Jews could pray and celebrate their own way. However, this increase in plurality lead to an increase in corruption and alHakim had to stop his own guards from enacting revenge on disobedient citizens. He was also forced to fire his vizier, Husayn, who was still pushing the Ismaili regulations. At the same time, the surrounding Abbasids began circulating inflammatory information about the lineage of the Fatimids. Conversely, a transcendental sect of Ismailis known as the Druze also formed around this time and spread the belief that the same soul that was bestowed to Prophet Adam transposed into each successive prophet and then the Ismaili Imams. alHakim was assassinated by four men (at the command of Sayf adDawla from the Hamdanid Dynasty) in his secret and expensive observatory. One of the assassin's was captured, along with evidence of his crime and brought before the new Imam. The Druze believe that alHakim wasn't murdered and actually transcended from his observatory to Heaven and will return to Earth again.
Abu Maad Ali azZahir was born in Cairo and succeeded to the Imamat when he was seventeen. His aunt Sitt alMulk, alHakim's sister, handled administrative work until azZahir came of age. alMulk chastised corrupted officials and appointed a special council. She avenged her late brother's death, by ordering the murder of Sayf adDawla, founder/amir of Aleppo. alMulk passed away from old age and azZahir took over the empire at the age of twenty-two. Soon after, the Nile failed to rise again and famine spread through Egypt: crops died, there was massive inflation, slaves revolted, and pilgrims and travelers were regularly attacked by looters. Because of the lack of funds, the Fatimids began to lose some of their territories in Syria but azZahir brokered peace with Byzantium in order to maintain them. azZahir implored the wealthy of Cairo to assist the citizens, but he received little to no help. After three years, the waters of the Nile rose again and Egypt slowly recovered. azZahir embraced art and music (and precious stones) and opened up schools for slaves and an armament factory. He even married a slave. He also sent Dais to Baghdad in order to convert the Iraqis to Ismailism. After sixteen years of Imamat (thirteen of flourishing in the role), azZahir died of the plague.
Imam alMustansir Billah
Imam alMustansir Billah succeeded to the Imamat when he was seven years old. The empire was ruled by vizier Jarjarai (who also served the previous two Imams) until his own death. Then Abu Saad, who had once owned alMustansir Billah's slave mother, tried to take over. The other advisers noticed his treachery and had him assassinated. This enraged alMustansir Billah's mother, who then ordered the murder of three advisers. With the young alMustansir Billah out of the public eye, a man named Sikkin impersonated Imam alHakim: he claimed he had come out of hiding, gathered some followers, and tried to attack alHakim's palace before he was arrested and sentenced to death. The Fatimid Empire also began to dissolve with various ethnic groups fighting amongst each other. The empire lost Sicily completely. While the Caliphate didn't attempt to regain these lost territories, this separation, combined with the continued rivalry with the Abbasids and the rising of the Seljuk conquest complicated trade routes in and out of the empire. Because of the ethnic conflicts within the empire, alMustansir Billah called on the help of Badr alJamali from Syria, who quelled uprisings around Cairo for almost 40 years. alMustansir Billah appointed his elder son Nizar as the next Imam, but Fatimid leadership (including now-vizier alJamali) preferred his younger son, Mustaali. alMustansir Billah asked Dai Hassan bin Sabbah to help secure Nizar's Imamat, but Sabbah was arrested by alJamali. After his escape from prison in Cairo, Hassan bin Sabbah fled to Persia where he spread the Ismaili Mission and worked to secure a safe place for the Imamat.
After the death of Imam alMustansir Billah, Mustaali was declared the Imam by Fatimid leadership; Sabbah however affirmed Nizar as the rightful Imam (as instructed by Imam alMustansir Billah), severing the connection between Egyptian Ismailis and Persian Ismailis and creating a new Ismaili State. However, the Ismaili State in Persia were surrounded by unfriendly Seljuk and Sunni forces, so Sabbah set out to secure the community's safety with a series of mountainous fortresses. News of Sabbah's work reached the Fatimid Caliphate in Egypt and worried the leadership. In retaliation, Mustaali ordered the imprisonment and execution of his brother, Nizar.