1. Foundation – Administration (Political – Ecclesiastical)

The Late Roman / early Byzantine province of Bithynia was founded by Emperor Diocletian (284-305); its capital was Nikomedeia, see of the governor of the province as well as of the metropolitan of Nikomedeia. A former part of the vast Roman province of Bithynia and Pontos, it occupied the northwest corner of Asia Minor, while for a short period, from 293 to the early 4th century, together with Paphlagonia¹ they formed asingleprovince. Nikomedeia, where was Diocletian's residence, was the administrative centre of the wider province of Bithynia. In 314 the province of Bithynia came under the newly established Diocese of Pontos, a geographical unity of mainly economical and, secondarily, administrative importance. The mint of Pontos was in Nikomedeia, although the city was not the seat of the vicar of Pontos, the officer in charge of the diocese.² Nicaea, Chalcedon, Kios, Appolonias, Apameia and Prousa were also important cities. In Hierocles' Synecdemos, a list of the cities of the Empire compiled in the first quarter of the 6^th century, no less than sixteen cities have been included in the province of Bithynia. Some time later, in the second quarter of the 6th century, the officer in charge held the rank of the consularis.

According to the first ecclesiastical taktika of the Patriarchate ofConstantinople, there were thirteen bishoprics in the early Byzantine Bithynia. The proceedings of the First Ecumenical Council were signed by nine bishops and two country bishops. There were three metropolises in the province, in Nikomedeia, Nicaea and Chalcedon, as well as the sees of the Arian Church and the Monophysite Church, which both disappeared later. The promotion of the bishopric of Nicaea to the rank of metropolis, as a result of Imperial will, during the proceedings of the First Ecumenical Council in 325, was renounced by the ecclesiastical hierarchy. However, Chalcedon was similarly promoted during the Fourth Ecumenical Council in 451, although it was not offered any bishoprics. Throughout the following centuries the Church disputed the Imperial privilege established in Bithynia.³

In the middle Byzantine period the area was divided and became part of the Opsikionand the Optimaton themes. The last time the province of Bithynia is ever mentioned dates back to the early 8^th century. The name was engraved on a seal; as for its absence ever since, it has been connected with the settlement of the Slavs in the area.⁴

Bithynia adjoins the Black Sea to the north and the Sea of Marmara to the west. The northwest part of the district forms the east coastline of the Dardanelles, the straits that connect these two seas. To the east it was bordered by the province of Paphlagonia⁵, to the south by the provinces of the Diocese of Asia, Hellespont, Phrygia Pacatiana (southwest) and Phrygia Salutaris (south and southeast) It should be pointed out that the southwest part of Bithynia adjoined the outskirts of Kyzicos, the metropolis of the Hellespont, where the mint of the Diocese of Asia was situated.⁶

2. The Strategic Importance Of Bithynia

Because the province of Bithynia was in the vicinity of Constantinople, it was part of the wider defensive zone of the capital of the Empire. Consequently, it was an area of high strategic importance both for the Byzantines and for their enemies. When Diocletian (284-305) arranged the road network, the natural obstacles formed by the narrow and long gulf of Nikomedeia and the mountain range of Olympos were by-passed. Seven army corpses were assigned with the protection of Bithynia, two of which were located in Constantinople. The rest of them were located in Kios, Prousa, Kotyaion, Dorylaeum, Appolonias and Nikomedeia. The fortifications of Bithynia, apart from the citadels and the ancient city walls, were built later. Bithynia was enforced in the military domain after the establishment of the themes. In the middle Byzantine period the positions Malagina, where the Imperial stud farm was located, and Lopadion, were two of the seven camps the Byzantine army used in order to launch its operations to the east.

The protection and promotion of the capital’s interests presupposed the control over Bithynia. The usurper Prokopios was proclaimed Emperor of the Romans in 365 in Kyzicos of the Hellespont. The cities of Bithynia immediately stood by his side and through these cities he directed to Constantinople to dethrone Valens (364-375). Zeno (474-475/476-491), deposed since 476, debouched from the position Pylai in order to take his throne back from the usurper Markian. From this position Emperor Heraclius (610-641) launched his expedition against the Persians in 622. During the riot of Artabasdos (741-743), the operations against the deposed Constantine V Kopronymos (740/741-775) took place mainly in the province of Bithynia. Besides, the riot broke out in Dorylaeum, within the territory of Bithynia.

Both the Persians and the Arabs attacked the cities of Bithynia on their way to Constantinople in the beginning and in the end of the 7^th century, and in the beginning and in the end of the 8^th century respectively, as well as during the 9^th century. The area was repeatedly plundered, while it was the theater of lots of sieges and conflicts. During the siege of Constantinople by the Arabs in 717/8 the besiegers remained at the outskirts of Chalcedon for one year, until they were deprived of any supplies and were forced to retreat in a pitiful condition.

3. Geopolitical Importance

Towards the end of the 3^rd century and in the first two decades of the 4^th century, the metropolis of the province of Bithynia was one of the four capital cities of the Roman Empire, by virtue of the administrative system of tetrarchy, introduced by Diocletian (284-305), while the area around it formed its district. The road network of Bithynia was further developed by Diocletian in order to establish a connection between Nikomedeia and the rest of the Empire. The link between Ankyra, in central Asia Minor, and the province of Europe had already been established since the 2^nd century, through the ports of Bithynia and the cities of Nikomedeia and Nicaea. When the administrative role of the city was later degraded by Constantine I(the Great)(314/24-337), who abolished the system of tetrarchy and promoted the neighbouring New Rome/ Constantinople to imperial capital, the infrastructure of Bithynia continued to support the communication network of the Empire, mainly by sea, with the sea route Constantinople - Nikomedeia. According to the comment of a scholar on the role of the two cities, it was the development of these new administration centres of the Empire that transformed the road network of Asia Minor, by transferring the main routes to the north and demanding that a network of regional roads be organised beyond Ankyra with a north/northwest orientation⁷. The northern coastline of the province together with the coastal cities of the other provinces of the Diocese of Pontos, with which it was connected by road and sea, formed a single geographical unity.

4. Economy – Culture

Both the northwest part of the province of Bithynia and its coastal zone were mainly regarded as the surroundings of the imperial capital. The area maintained the cosmopolitan character it had acquired in the late Roman period. It remained a popular place among the aristocrats of the capital, who used to build their luxurious country houses there. The hot springs at Pythia were the favourite health spas of the citizens of Constantinople. A palace was built early on near the springs. Moreover, Bithynia, close to the spiritual and intellectual centre of the Empire, was largely influenced by the artistic and spiritual trends of the capital while, on the other hand, it developed its own cultural activity.

In addition, due to some geographical details, monastic complexes were founded end developped, which, like any Bithynian place of cult, were favoured by the prestige and financial standing of visitors and worshippers. The most important monastic complexes were Mount Olympos, the monastery of Saint Auxentios and the monastery of Sakkoudion, founded in the late 8^th century. Besides, thanks to frequent donations from aristocrats and even Emperors, soon enough bethels, charitable trusts and a hospital in Nikomedeia were added to other secular structures, which had always served as residence for the aristocrats in Bithynia. These Bithynian institutions possessed land from donations in Cappadocia, Galatia and Thrace.

The coastal positions of Pylai, Helenopolis and Prainetos operated as anchorages, 'modest but functional', since they were linked with important hubs, such as Kios and Nikomedeia. In such positions, but also in some minor ones, as well as along the dense road network there were emporiums, kommerkia, shopping arcades and several hotels. The cities were full of markets. The mint and the arms handicraft in Nikomedeia as well as the potteries in Nicaea and elsewhere promoted their products primarily to the capital and to the Balkans as well. The few important cities of the province of Bithynia thrived. The commercial and military routes served the transport of both goods to the capital and troops to the camps of the praetorian prefecture of Oriens (praefecura praetorio per Orientem). The agricultural and livestock production of Bithynia was remarkable. Grains, olive oil, salt and wine were produced in massive amounts. Viniculture was particularly developed. Vines in Tarsia were up to five metres high. An important river, Saggarios, and lots of other minor rivers crossed the fertile Bithynian land. The lakes of Appolonias and Ascania, near Nicaea and to the east of Nikomedeia, as well as the coasts, were good places to fish. Mount Olympos provided timber. The regeones and the salta (large estates with settlements, fortified and military enforced) created diverse natural scenery.

Major natural disasters, such as earthquakes and floods, occurred in the 4^th century. Nikomedeia and Nicaea were plagued by such disasters. Although their buildings were partly rebuilt after the earthquake had struck the cities, Nikomedeia in particular did not recover quickly. The city’s aqueduct was restored by Justinian I (527-565). Epidemics struck both animals and humans during the reigns of Valens (364-375) and Justinian I. The most devastating floods in the early Byzantine province of Bithynia happened in the times of Theodosios II (408-450) and Leo I (491-518).