Byzantine Empire in 650 under Constans II.
When Heraclius died in 641, his death precipitated a dynastic struggle. He was succeeded by two of his sons: Constantine, his son by his first marriage to Eudokia, and Heraclius, known as Heracleonas, his son by his second wife, Martina, who was also his niece. Martina herself was given a special role to play as augusta. Heraclius’ marriage to his niece after the death of Eudokia had met with opposition at the time, and there was opposition to the association of Martina as empress with the two emperors. Constantine’s death (from poisoning, according to a rumour reported by Theophanes) only increased opposition to Martina and Heracleonas, and there were demands that the imperial dignity be shared with Constantine’s son, also Constantine, but usually called Constans. As troops from the Anatolian armies appeared at Chalcedon in support of these demands, Heracleonas seems to have acceded to them. Nevertheless, Heracleonas and his mother, together with her other two sons, were deposed and exiled, and Constans II became sole emperor.
Constans inherited the continuing collapse of the eastern provinces to the Arabs. Egypt was slipping away; Arab raids into Armenia began in 642-3. In 647 Mu`awiya led a raiding party into Anatolia and besieged Caesarea, whence they penetrated still more deeply into Anatolia. The Arabs made no attempt to settle there, but huge amounts of booty were taken back to Damascus. Mu`awiya also realised the need for the Arabs to develop sea power, and in 649 he led a naval expedition against Cyprus in which Constantia was taken. In 654 Rhodes was laid waste, Kos taken and Crete pillaged. The following year, in an attempt to destroy the threat to Byzantine control of the sea, the Byzantine fleet, under the command of the emperor Constans himself, engaged with the Arab fleet but was itself defeated, Constans himself barely escaping with his life. The death of the caliph `Uthman in 656 precipitated civil war amongst the Arabs between Mu`awiya, proclaimed caliph in Syria, and `Ali, the Prophet Muhammad’s son-in-law. The civil war ended with the death of `Ali and the establishment of the Umayyad dynasty under Mu`awiya in 661-2: events that provoked the schism in Islam between Sunni and Shi`ite that still endures. However, those years of civil war provided valuable respite for the Byzantines. Constans was able to turn his attention to the Balkans, where the power of the Avars had waned, and in 658 he led an expedition into the Sklaviniai, the regions settled by the Slavs, where, according to Theophanes, he met with considerable success and was able to use Slav prisoners thus taken to repopulate areas in Anatolia that had been devastated or depopulated. This policy of repopulating Anatolian regions by Slavs was to be continued by his successors, Constantine IV and Justinian II.
In 662 Constans II and his court moved to Syracuse in Sicily. This attempt to abandon the beleaguered Constantinople and re-establish the court of the Roman Empire closer to the centre of the truncated empire, recalls earlier plans by both Heraclius and Maurice, and reveals that there was no sense that the Byzantine Empire was now confined to the eastern Mediterranean. From his base in Sicily, Constans clearly intended to liberate Italy from the Lombards. Before arriving at Syracuse, he had led a campaign in Italy, which had met with some success, though he had failed to take Benevento and soon retired to Naples, whence he made a ceremonial visit to Rome. But his residence in Sicily was extremely unpopular, imposing as it did an unwelcome financial burden on the island. There was fierce opposition in Constantinople to the loss of the court, and in 668 he was assassinated by a chamberlain.
Constans II was succeeded by his son, Constantine IV. It was during his reign that the Umayyad caliph Mu`awiya made a serious attempt to complete the Arab expansion that had begun in the 630s, to take Constantinople, and with it destroy the only serious opposition to Arab rule in the Mediterranean. After his victory over `Ali in the Arab civil war, Mu`awiya renewed his offensive on the Byzantine Empire. By 670 the islands of Cyprus, Rhodes and Kos, and the town of Kyzikos on the southern coast of the Sea of Marmara had all been occupied by Arab naval forces. In 672 Smyrna was taken, and in 674 the main attack on Constantinople began. A large Arab fleet blockaded the city, and for the next four years the same fleet was to blockade Constantinople, retiring in the winter to shelter off Kyzikos. Each year the defences of Constantinople stood firm, and in the final naval battle the Byzantines secured a major victory. This was achieved by their use of Greek fire, first mentioned in the sources on this occasion. It was a highly inflammable liquid, presumably based on crude oil, that was projected in a stream on to the enemy ships, causing them to burst into flames. At the same time as this naval victory, the Byzantine army was able to surprise and defeat an Arab army contingent in Anatolia. Mu`awiya was forced to break off his attack on Constantinople and sue for peace. This major victory for the Byzantines proved to be a turning point: the Arab threat to Constantinople was withdrawn for the time being, and Byzantium’s prestige in the Balkans and the West was enhanced. Embassies from the khagan of the Avars (now restricted mainly to the Hungarian plain) and from the Balkan Slavs arrived in Constantinople, bringing gifts and acknowledging Byzantine supremacy.
The situation in the Balkans was, however, about to change. The Slavs in the Balkans had never formed any coherent political entity, though their presence confined the Byzantines to Thessaloniki, and other coastal settlements. An Asiatic group, the Bulgars, had long been a presence among the nomadic tribes of the Eurasian plain. The Byzantines had had friendly relationships with them, and had supported them against the Avars. With the arrival of another group, the Khazars, the khaganate of the Bulgars, whose homeland was to the north of the Sea of Azov, began to split up, and one group, led by Asparuch, arrived at the Danube delta in 670, intending to settle south of the Danube in traditionally `Byzantine’ territory. The Byzantines saw no threat in the Bulgars, but were unwilling to allow them south of the Danube. In 680, a Byzantine fleet arrived at the mouth of the Danube and Byzantine troops moved up from Thrace, intending to expel the Bulgars. The Bulgars avoided open battle but, as the Byzantine forces withdrew, they took them by surprise and defeated them. Constantine IV concluded a treaty with Asparuch, which granted the Bulgars the territory they already held. As a result of the Bulgar presence, several Slav tribes hitherto loyal to Byzantium recognised the overlordship of the Bulgars. So there began to come into being a Bulgar-Slav country with its capital at Pliska. This independent, and often hostile, presence so close to Constantinople, in principle able to control the route from the Danube delta to Constantinople, was to prove a long-standing threat to the stability of the Empire.
The latter part of Constantine’s reign saw the Byzantine Empire regain a certain stability. In 684/5 he led a successful military expedition into Cilicia, which forced the caliph `Abd al-Malik to sue for peace and pay tribute to the Byzantines. Religious reconciliation with Rome led to peace in Italy with the Lombards, brokered by the pope. In North Africa, the Byzantines were able to halt the advance of the Arabs through alliances with Berber tribes, though this only bought time until the Berbers themselves converted to Islam.
Constantine IV died in 685 and was succeeded by his son, Justinian II. It is worth noting that both Constantine IV and Constans II had deposed their brother(s) in the course of their reign – in Constantine’s case despite open opposition from the senate and the army – to secure the succession of their eldest son. Justinian sought to build on the relative stability achieved by his father, leading an expedition into the Balkans and reaching Thessalonica. He continued the policy of his father and grandfather of transporting Slavs into Anatolia, and also transported some of the population from Cyprus to Kyzikos, that had been depopulated during the siege of Constantinople, and Mardaites from North Syria and Lebanon to the Peloponnese and elsewhere. His breaking of the truce with `Abd al-Malik in 692-693 by attacking Arab forces in Iraq turned to disaster when his Slav troops deserted. As a result the Armenian princes once again acknowledged Muslim suzerainty.
In 695, Justinian was overthrown in a palace coup, and replaced by Leontius, the recently appointed general of the thema of Hellas. Justinian had his nose slit and was exiled to the Cherson, where his grandfather had earlier exiled PopeMartin. Leontius’ reign lasted three years, during which he witnessed the end of Byzantine rule in North Africa. That defeat, and the consequent loss of Carthage, provoked another rebellion in which Leontius was deposed in favour of Apsimar, the droungarios of the Kibyrrhaiot fleet, who changed his name to the more imperial-sounding Tiberius. Tiberius Apsimar reigned from 698 to 705, during which time Asia Minor was subject to continual Arab raiding. He was replaced by Justinian, who returned with the support of the Bulgar khan Tervel, making his way into the city through one of the aqueducts. Justinian’s final six years – years of terror and vengeance – were brought to an end by a military coup. Thereafter, until the accession of Leo III in 717 (the emperor who a decade or so later was to introduce Iconoclasm), three military leaders succeeded one another for reigns that were short and inglorious.