1. Historical background
In the beginning of the 9th century the struggle between the Byzantines and the Arabs was escalating, because of the refusal of the emperor Nikephoros I to continue paying the Arabs the annually submission tax which was agreed by the empress Eirene and the al-Mahdi in 782.1 To this decision, which forms part of the general effort of Nikephoros to strengthen the economy of Byzantium, the Arabs reacted immediately, and already in 803 they launched raids on byzantine territory. The responsibility of the defence of the eastern frontier was given to Vardanes, the so-called Tourkos (Turk), of the of Anatolikon and also of the five themata of Asia Minor. The former, however, mutinied, on the 19th of July 803, against Nikephoros I and, although his movement was soon -in approximately two months- oppressed, this weakened the defence of the empire in a certain degree. Thus, in August 804, a new Arab attack resulted in a defeat of the Byzantine army, under the direct command of emperor Nikephoros, at Krassos of Phrygia.
However, problems in the area of Chorasan2 prevented the caliph Hārūn ar-Rashīd, successor of al-Mahdi to continue the fight against the Byzantines and he preferred to sign a peace treaty with them. In the time to follow, Nikephoros took advantage of the inactivity of the Arab caliph and strengthened the defence of Asia Minor, building or repairing fortifications at Ankara, Andrasos and Thebasa,3 whereas the Byzantine troops launched raids in Cilicia and Melitene, which was under Arab control since the middle of the 8th century. As soon as Hārūn ar-Rashīd solved his problems in Chorasan (November 805), he started the preparations for a campaign against Cappadocia, in order to stop the strengthening of the Byzantine position in this area and to stop their advance towards the east, which seemed probable.
2. Beginning and outcome of the campaign
On June 11, 806 the Arab caliph Hārūn ar-Rashīd, having gathered in Rakka of Mesopotamia a large army,4 launched his campaign against the region of Cappadocia, along the Arab-Byzantine frontier. Through the Gates of Cilicia Hārūn invaded the imperial territory and seized Tyana, where he built fortifications and erected a mosque. Then, a part of the Arab army moved towards the north, conquered Andrasos, Malakopea, Sideropalos and Kyzistra and advanced as far as Ankara, without, however, conquering the city.5 Meanwhile, Hārūn ar-Rashīd advanced towards the west and, after a siege that lasted one month, conquered Heraclea (between August 20 and September 17), as well as the nearby city of Thebasa. The fall of Herakleia was followed by the city's sack and destruction, whereas the inhabitants were imprisoned and deported from the city. In order to face the Arab attacks in Asia Minor, Nikephoros organized a campaign against them, led by himself,6 but the numerical superiority of his adversary forced the emperor to come into negotiations for the signing of a peace treaty. The Byzantine embassy was comprised of three clerics, led by Michael, metropolitan of Synada.7
According to the unfavourable for the Byzantines peace treaty signed, Nikephoros was obliged to pay the Arabs immediately, but also annually from that year on, 30,000 pieces of gold,8 in which six more coins were added, three as a poll tax for him and three for his son and co-emperor Stavrakios. Also, he pledged not to rebuild Herakleia or any other Byzantine fort which was destroyed by the Arabs during this campaign. In exchange to all this, Hārūn ar-Rashīd agreed to withdraw his forces from the Byzantine territory.
Probably the most severe blow by the campaign of Hārūn ar-Rashīd in Cappadocia in 806, was the temporary seizure of the fort of Herakleia, which controlled the road the Arabs often followed during their raids, that is from the Gates of Cilicia towards the hinterland of the Byzantine Empire. The Arabs apparently gave special importance to the seizure of Herakleia,9 probably because they greatly appreciated the importance of this specific fort.
In reality, however, although Hārūn ar-Rashīd attacked the Byzantine Empire leading a large military force, his operation did not cost important casualties to the Byzantines, since after the withdrawal of the Arabs, Nikephoros violated the treaty and rebuilt the destroyed forts, whereas at the same time he refused to pay the conditioned tax again. Besides, the death of Hārūn ar-Rashīd in 809 and the subsequent domestic unrest in the Caliphate favoured the Byzantines.
Nevertheless, even this brief seizure of important forts of Asia Minor by the Arabs proved their military superiority against the Byzantines, something which suspended Nikephoros’ plans to expand his power to the east. Thus, in the rest of his reign, Nikephoros never organized any military operation in Asia Minor against the Arabs again, focusing his foreign policy on the Balkan region.
1. According to this treaty, the annual tax which the Byzantines had to pay to the Arabs reached the amount of 70,000 (or 90,000) denars.
2. The great discontent towards the governor of the province of Chorasan (today NE Iran) forced the caliph to personally visit the area (April 805).
3. Nikeforos wanted to strengthen the forts which were under the constant attacks by the Arabs, as they were near the borders with Cilicia, the usual starting point of the Arab raids. More specifically, however, it is possible that the fortifications of Ankara had been damaged by the raids of 799, whereas Thebasa was ruined after its conquest by the Arabs in 793.
4. It numbered 135,000 men and, according to W. T. Treadgold (The Byzantine Revival 780-842 [Stanford 1988], p. 144), it was the largest army mustered during the time of the Abbasids. Theophanes, on the other hand, in his Chronography (ed. de Boor, C., Theophanis Chronographia [Leipzig 1883], p. 482, 3) mentions 300,000 men, a number considered excessive also by Αικατερίνη Χριστοφιλοπούλου (Βυζαντινή Ιστορία 2/1: 610-867 [Thessaloniki 1993], p. 174).
5. Theophanes, Chronographia, ed. de Boor C., Theophanis Chronographia (Leipzig 1883), p. 482, 7-8.
6. Theophanes, Chronographia, ed. de Boor C., Theophanis Chronographia (Leipzig 1883), p. 482, 8-10. The exact date of the campaign remains uncertain.
7. The other two clerics were the abbot of the monastery of Goulaios and the steward of the metropolis of Amastris: Theophanes, Chronographia, ed. de Boor C., Theophanis Chronographia (Leipzig 1883), p. 482, 11-12.
8. The Arab historian al-Tabari mentions 50,000 pieces of gold and extra four for Nikeforos and two for Stavrakios. This information has been accepted by R. J. H. Jenkins (Byzantium: The Imperial Centuries (AD 610-1071) (London 1966), p. 120.
9. The impact this event had on Arab sources is analogous to the later seizure of Amorion (838) by the caliph Mutasim, which was indeed an important event. On the contrary, the Byzantine historians do not distinguish the fall of Herakleia from the fall of the rest of the forts of Cappadocia.