Byzantine Empire

The Byzantine Empire (or Byzantium) was the predominantly Greek-speaking remnant of the Eastern Roman Empire throughout Late Antiquity and the Middle Ages.

History
Known simply as the Roman Empire (Greek: Βασιλεία Ῥωμαίων, Basileia Rhōmaiōn) or Romania (Ῥωμανία, Rhōmanía) by its contemporaries, the Empire was centered on the capital of Byzantium (later renamed Constantinople under Emperor Constantine) and was ruled by emperors in direct to the ancient Roman Emperors after the collapse of the Western Roman Empire.

Late antiquity
In this time and after, between the 4th and 10th centuries, the Byzantines recaptured vital territory in North Africa, the Balkans, and even the Italian city of Rome. From 640 to 698, Byzantine North Africa came under assault and fell to more Arab forces. In the years from 674 to 717, the Arabs are finally defeated in one place: Constantinople. Siege after siege, the Arab armies were determined. However, the Byzantines giant walls, dedicated navy, and their secret weapon, the Greek Fire, prevented the capital of their empire from falling.

Early Middle Ages
At the start of the Middle Ages, the Empire was the most powerful Christian Nation. They became so powerful that the Byzantines were forced to ask the Pope in Rome for aid, leading to the Crusades. These Crusades were meant to retake areas for the Byzantines, but instead the Crusaders took territory for themselves. Mistrust in the Byzantines even caused Crusaders to take some Byzantine territory.

These attacks culminated in the Fourth Crusade in 1204. The Venetian Doge Dandalo, with the support of Catholic crusaders, sacked Constantinople after promising a disposed Byzantine Emperor that they would restore him. Instead, a Latin Kingdom held onto this territory until 1261. After retaking their capital, the Byzantine Empire declined rapidly, due to civil strife and a new foe: The Ottoman Empire.

Fall of the Empire
Without support from other Christian nations after years of mistrust, the Byzantine territories were taken piece by piece bythe rising Ottoman Empire. Eventually, every Byzantine territory was taken by the Ottomans and Constantinople was surrounded. Finally, after a last stand in the defense of Constantinople by the last emperor, Constantine XI Palaeologos, the Empire fell in 1453 due to the decisive siege conducted by Sultan Mehmed II. By 1511, the remnants of the Empire were still headed by the House of Palaiologos under Manuel Palaeologos.

Infiltration of the Templars
During the early 16th century after the Templars were driven from Italy by the Assassins, Ezio Auditore da Firenze mostly responsible for their downfall, the Templars fled. They were able to seize control of the remnants of the Byzantine Empire. Now in control of the Byzantine remnants, the Templars set up their primary headquarters at Cappadocia. The Byzantine then aimed to uproot the Ottomans and take control of Constantinople.

Masyaf
Eventually, the Templars showed great interest in Altaïr Ibn-La'Ahad's five seals. Because of this, many Byzantine soldiers went to Masyaf with their Templar masters in an attempt to recover the seals or gain a better understanding of them. The Byzantine soldiers were able to recover at least one of the five seals, which was later kept in by their commander and Templar master, Leandros. However, eventually the seal was stolen by Ezio Auditore, who also sought all five seals and killed Leandros.

Constantinople
As the Templars plotted to overthrow the Ottomans, many Byzantine soldiers were present in Constantinople at the time. By 1511, they rivalled the Constantinople Assassins Guild. At one point, a group of Byzantine soldiers attacked the Galata District, though were driven away by the Assassins. The Byzantine remnants were able to secure several strongholds across Constantinople as their Templar leaders plotted against the Ottomans. However, the Assassins took the strongholds for themselves and converted them into Assassin Dens. At some point, Cappadocia was infiltrated by Ezio.