The themes or thémata were the main military and administrative divisions of the middle Byzantine Empire. They were established in the mid-7th century in the aftermath of the Slavic migrations to Southeastern Europe and Muslim conquests of parts of Byzantine territory, and replaced the earlier provincial system established by Diocletian and Constantine the Great. In their origin, the first themes were created from the areas of encampment of the field armies of the East Roman army, and their names corresponded to the military units that had existed in those areas. The theme system reached its apogee in the 9th and 10th centuries, as older themes were split up and the conquest of territory resulted in the creation of new ones. The original theme system underwent significant changes in the 11th and 12th centuries, but the term remained in use as a provincial and financial circumscription until the very end of the Empire.
Staurakios or Stauracius was the shortest-reigning Byzantine emperor, ruling for 68 days between 26 July and 2 October 811.
Bardas was a Byzantine noble and high-ranking minister. As the brother of Empress Theodora, he rose to high office under Theophilos. Although sidelined after Theophilos's death by Theodora and Theoktistos, in 855 he engineered Theoktistos's murder and became the de facto regent for his nephew, Michael III. Rising to the rank of Caesar, he was the effective ruler of the Byzantine Empire for ten years, a period which saw military success, renewed diplomatic and missionary activity, and an intellectual revival that heralded the Macedonian Renaissance. He was assassinated in 866 at the instigation of Michael III's new favourite, Basil the Macedonian, who a year later would usurp the throne for himself and install his own dynasty on the Byzantine throne.
The Byzantine navy was the naval force of the Byzantine Empire. Like the state it served, it was a direct continuation from its Roman predecessor, but played a far greater role in the defence and survival of the state than its earlier iteration. While the fleets of the Roman Empire faced few great naval threats, operating as a policing force vastly inferior in power and prestige to the army, command of the sea became vital to the very existence of the Byzantine state, which several historians have called a "maritime empire".
Petronas was a notable Byzantine general and leading aristocrat during the mid-9th century. Petronas was a brother of Empress Theodora and hence brother-in-law of Emperor Theophilos, under whom he advanced to the high court rank of patrikios and the post of commander of the Vigla guard regiment. After Theophilos' death, he played a role in the ending of Iconoclasm, but was sidelined along with his brother Bardas during the minority of his nephew, Michael III, when power was held by the regent Theoktistos. In 855, Petronas and Bardas encouraged Michael III to seize control of the government: Theoktistos was murdered, Theodora banished to a monastery, Bardas became Michael's chief minister, and Petronas was tasked with the war against the Arabs. In 863, he scored a crushing victory at the Battle of Lalakaon, a feat which marked the gradual beginning of a Byzantine counter-offensive in the East. Promoted to the rank of magistros and the office of Domestic of the Schools, he died in 865.
Theoktistos or Theoctistus was a leading Byzantine official during the second quarter of the 9th century and the de facto head of the regency for the underage emperor Michael III from 842 until his dismissal and murder in 855. A eunuch courtier, he assisted in the ascent of Michael II to the throne in 820, and was rewarded with the titles of patrikios and later magistros. He held the high posts of chartoularios tou kanikleiou and logothetēs tou dromou under Michael and his son Theophilos. After Theophilos' death in 842, Theoktistos became a member of the regency council, but soon managed to sideline the other members and establish himself as the virtual ruler of the Empire. Noted for his administrative and political competence, Theoktistos played a major role in ending the Byzantine Iconoclasm, and fostered the ongoing renaissance in education within the Empire. He also continued the persecution of the Paulician sect, but had mixed success in the wars against the Arabs. When Michael III came of age in 855, his uncle Bardas persuaded him to throw off the tutelage of Theoktistos and his mother, the Empress-dowager Theodora, and on 20 November 855, Theoktistos was assassinated by Bardas and his followers.
The Muslim conquest of Sicily began in June 827 and lasted until 902, when the last major Byzantine stronghold on the island, Taormina, fell. Isolated fortresses remained in Byzantine hands until 965, but the island was henceforth under Muslim rule until conquered in turn by the Normans in the 11th century.
Umar ibn Hafs ibn Shuayb ibn Isa al-Balluti was the leader of a group of Andalusi refugees who seized control of Alexandria and, after being expelled from the city by the Abbasids, conquered the Byzantine island of Crete, becoming the first Emir of Crete.
The Battle of Mauropotamos was fought in 844, between the armies of the Byzantine Empire and the Abbasid Caliphate, at Mauropotamos. After a failed Byzantine attempt to recover the Emirate of Crete in the previous year, the Abbasids launched a raid into Asia Minor. The Byzantine regent, Theoktistos, headed the army that went to meet the invasion but was heavily defeated, and many of his officers defected to the Arabs. Internal unrest prevented the Abbasids from exploiting their victory, however. A truce and a prisoner exchange were consequently agreed in 845, followed by a six-year cessation of hostilities, as both powers focused their attention elsewhere.
The Emirate of Crete was an Islamic state that existed on the Mediterranean island of Crete from the late 820s to the reconquest of the island by the Byzantine Empire in 961. Although the emirate recognized the suzerainty of the Abbasid Caliphate and maintained close ties with Tulunid Egypt, it was de facto independent.
The Thracesian Theme, more properly known as the Theme of the Thracesians, was a Byzantine theme in western Asia Minor. Created either in the mid-7th or the early 8th century as the settlement of the former Army of Thrace, after which it was named, it was one of the larger and more important themes of the Empire throughout its existence based on its proximity to Constantinople. The Thracesian Theme was one of the longest-lived themes, surviving until the region was conquered by the Turks in the early 14th century.
The Opsician Theme or simply Opsikion was a Byzantine theme located in northwestern Asia Minor. Created from the imperial retinue army, the Opsikion was the largest and most prestigious of the early themes, being located closest to Constantinople. Involved in several revolts in the 8th century, it was split in three after ca. 750, and lost its former pre-eminence. It survived as a middle-tier theme until after the Fourth Crusade.
The Theme of Hellas was a Byzantine military-civilian province located in southern Greece. The theme encompassed parts of Central Greece, Thessaly and, until c. 800, the Peloponnese peninsula. It was established in the late 7th century, and was broken up into smaller districts in the late 11th/early 12th century. The theme fell to the Crusader army led by Boniface of Montferrat in 1205.
The Theme of Cephallenia or Cephalonia was a Byzantine theme located in western Greece, comprising the Ionian Islands, and extant from the 8th century until partially conquered by the Kingdom of Sicily in 1185.
Elpidius or Elpidios was a Byzantine aristocrat and governor of Sicily, who was accused of conspiring against Empress Irene of Athens. This forced him to rebel, and after being defeated he defected to the Abbasid Caliphate and was recognized there as Byzantine emperor.
Photeinos was a Byzantine commander and governor active in the 820s.
Krateros was a Byzantine naval commander in the 820s.
The siege of Chandax in 960-961 was the centerpiece of the Byzantine Empire's campaign to recover the island of Crete which since the 820s had been ruled by Muslim Arabs. The campaign followed a series of failed attempts to reclaim the island from the Muslims stretching as far back as 827, only a few years after the initial conquest of the island by the Arabs, and was led by the general and future emperor Nikephoros Phokas. It lasted from autumn 960 until spring 961, when the main Muslim fortress and capital of the island, Chandax was captured. The reconquest of Crete was a major achievement for the Byzantines, as it restored Byzantine control over the Aegean littoral and diminished the threat of Saracen pirates, for which Crete had provided a base of operations.
The Byzantine conquest of Cilicia was a series of conflicts and engagements between the forces of the Byzantine Empire under Nikephoros II Phokas and the Hamdanid ruler of Aleppo, Sayf al-Dawla, over control of the region of Cilicia in southeastern Anatolia. Since the Muslim conquests of the 7th century, Cilicia had been a frontier province of the Muslim world and a base for regular raids against the Byzantine provinces in Anatolia. By the middle of the 10th century, the fragmentation of the Abbasid Caliphate and the strengthening of Byzantium under the Macedonian dynasty allowed the Byzantines to gradually take the offensive. Under the soldier-emperor Nikephoros II Phokas, with the help of the general and future emperor John I Tzimiskes, the Byzantines overcame the resistance of Sayf al-Dawla, who had taken control of the former Abbasid borderlands in northern Syria, and launched a series of aggressive campaigns that in 964–965 recaptured Cilicia. The successful conquest opened the way for the recovery of Cyprus and Antioch over the next few years, and the eclipse of the Hamdanids as an independent power in the region.
