Byzantine Diplomacy: Envoys, Alliances and Imperial Negotiation

Byzantine emperors appointed envoys to negotiate with neighbouring rulers. Interpreters carried discussions across languages, and imperial transport supported missions to and from Constantinople. Treaties could secure troops, settle frontier disputes or grant trading privileges. Marriages and court titles connected foreign rulers with the imperial dynasty; payments purchased specific settlements and military assistance.

Negotiations accompanied campaigns and changed with their results. Justinian paid for peace with Persia in 532, Basil II obtained troops from Vladimir of Kiev, and Alexios I sought Venetian naval help against the Normans. Each agreement supplied resources or security for a particular political problem.

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Imperial order and the realities of power

Byzantine rulers inherited the Roman belief that their emperor was the legitimate head of the oikoumene, the inhabited world. Christian ideas reinforced this political vision. The empire presented itself as the center of a divinely ordered community, with other rulers arranged around the emperor in different degrees of proximity. This hierarchy appeared in titles, correspondence, seating arrangements and ceremonial precedence.

The theory was not the same as direct control. Byzantine writers and officials had to reconcile universal claims with a frontier world in which many rulers were independent, powerful or openly hostile. The empire therefore treated neighboring states according to circumstances. Persian and later Arab rulers could be addressed as imperial “brothers,” while Christian rulers elsewhere might be described as spiritual relatives, kings or subordinate allies. Titles borrowed from the Byzantine court could honor a foreign prince while also defining the place that Constantinople assigned him within its political order.

This language could be contested. Simeon of Bulgaria, who had been educated at Constantinople, claimed the title of emperor of the Bulgarians and Romans and fought for recognition. In 927, Constantinople accepted the title of basileus for his successor Peter, while the Byzantine emperor retained the more expansive title of autocrat of the Romans.

Information, offices and the movement of envoys

Diplomacy began with information. Reports came from ambassadors, soldiers, merchants, missionaries and travelers. Officials gathered knowledge about the rulers, customs, resources, rivalries and military capacities of neighboring peoples. The so-called Bureau of Barbarians, attested from late antiquity into the tenth century, helped receive foreign envoys, maintain interpreters and collect information about the communities with which the empire dealt. Its work had both administrative and security purposes.

The diplomatic apparatus changed over time. Between the fifth and eighth centuries, the magister officiorum, a senior palace official, supervised departments concerned with imperial letters, audiences, interpreters and the state transport system. After the eighth century, responsibilities were redistributed. The logothete of the Drome became responsible for the imperial post, the movement of ambassadors and the corps of interpreters, while the master of ceremonies managed the reception of foreign missions.

Constantine VII’s De Administrando Imperio illustrates the practical character of this knowledge. Its discussions include how the Pechenegs might serve Byzantine interests, how imperial representatives should travel through their territory, how the Khazars might be confronted and how the peoples and rulers of different regions should be understood.

Emperors selected envoys from court officials, clergy, soldiers and interpreters according to the mission. Delegations carried instructions and letters, and could include people familiar with the destination’s language and customs.

Treaties, payments and the management of war

A treaty could establish peace, define borders, regulate military cooperation or specify a ruler’s position in relation to the emperor. Byzantine agreements sometimes took the form of a chrysobull, an imperial document authenticated by a golden seal. Their contents varied because they answered particular problems. An agreement might require a ruler to provide troops, protect a frontier, permit Byzantine movement through his territory or accept a Byzantine nominee.

Military service was often linked to financial reward. An agreement associated with Vladimir of Russia and Basil II in 987 provided 6,000 Varangians for Byzantine service. A settlement with the Serbian ruler in 1150 required 2,000 soldiers for European campaigns and 500 for Asian campaigns. Byzantine rulers could also provide a roga, an annual pension or allowance, to foreign leaders and allies. In one recorded payment, 700 Rus’ who took part in an expedition against Crete received 7,200 nomismata, gold coins used in the Byzantine monetary system.

The peace negotiated with Khosrau I in 532 required a Byzantine payment of 110 centenaria, or 11,000 pounds of gold. Procopius reports the sum alongside frontier terms, including the transfer of the Roman military command from Dara to Constantina. The agreement ended the current war and was proclaimed a perpetual peace.

Financial diplomacy worked alongside the policy of setting one potential enemy against another. Constantinople might support the Pechenegs against the Rus’, or seek the assistance of another steppe power when the Pechenegs themselves became dangerous. Constantine VII’s advice repeatedly asks which neighboring people could be used against which rivals.

Gifts, trade and imperial ceremony

Imperial workshops supplied fine textiles for diplomatic gifts. Silk could be carried to foreign courts and made into prestigious clothing. In the agreement with Simeon of Bulgaria in 924, Byzantium undertook to provide 1,000 richly embroidered silk tunics each year in return for his withdrawal from imperial territory.

Gifts could also respond to immediate needs. In 1053, Constantine IX sent grain to Egypt during a famine while seeking to prepare improved commercial relations. The Fatimid caliph responded with an elephant and a giraffe.

Officials received envoys, assigned lodgings and regulated their movement and access to the court. Audiences followed prescribed arrangements for approaching the emperor. Ceremonial dress and the placement of officials marked rank during the reception.

Liutprand of Cremona described his reception in Constantinople in 949, including a throne room with golden lions and mechanical birds. The performance was meant to impress, but it was also a political statement about imperial order and technical sophistication. The same principle could be used with powerful eastern rulers. When Manuel I Komnenos received Kilij Arslan II in 1161 or 1162, the program included races, illuminated displays, staged naval actions and costly vessels.

Prestige could turn into humiliation when negotiations failed. Liutprand’s embassy in 968 sought a marriage between a Byzantine princess and the son of Otto I. The request challenged Constantinople’s assumptions about the special status of women born in the imperial purple, and Liutprand’s conduct further damaged the mission.

Marriage, fosterage and religious ties

In 732, Constantine, the future Constantine V, married Tzitzak, daughter of the Khazar khagan Bihar. A granddaughter of Romanos I later married Peter of Bulgaria as part of the settlement of 927. Dynastic marriages supplied a personal relationship between the courts involved.

From the Komnenian period onward, marriages linked Constantinople more regularly to European courts. Manuel I Komnenos married a relative of the German ruler Conrad III, and Byzantine dynastic connections extended into Hungary and the western Mediterranean. In the late thirteenth century, Michael VIII arranged marriages for two daughters with Mongol rulers: Euphrosyne married Nogai Khan of the Golden Horde, while Maria married Abaqa Khan of Persia.

Foreign princes could also be brought to Constantinople for education, protection or political leverage. Their presence could serve as a guarantee for an agreement, while court upbringing familiarized them with Byzantine institutions and customs.

Christianization offered another means of creating durable ties, especially in eastern Europe. Missionaries could use local languages and adapt religious teaching to the communities they addressed. In the ninth century, Cyril and Methodius worked among the Khazars and later responded to the request of the Moravian ruler Rastislav for clergy able to teach in the local language. Their work included the development of the Glagolitic alphabet. Although their mission in Moravia did not remain dominant, their followers found support in Bulgaria, where the ruler Boris I accepted Christianity in 864 after conflict with Byzantium. The emperor Michael III acted as his sponsor, and Boris took the Christian name Michael.

The conversion of the Rus’ followed a similarly political and religious pattern, though over a longer period. The ruler Olga visited Constantinople in 945 or 957, according to different sources, and received an elaborate welcome. Under Vladimir, Byzantine assistance during a succession crisis was connected with an alliance, a marriage to the imperial princess Anna and Vladimir’s conversion. In 987, Vladimir also promised military support to Basil II, sending 6,000 Varangians.

Regional diplomacy and late imperial appeals

Relations with Persia were conducted between two states that regarded themselves as civilized empires. Their rulers could address one another as brothers even while fighting over borderlands. After the Arab conquest of the Sasanian Empire, caliphs inherited a position that Byzantine protocol treated with comparable respect, although relations followed a different political course. The ceremonial rules recorded under Constantine VII placed careful limits on precedence, titles and the form of imperial correspondence.

Agreements with Bulgaria and Serbia established boundaries, obligations and recognition of rulers. The settlement of 681 recognised Bulgarian rule in Moesia, while later agreements required particular contributions of troops or payments.

The Hungarian prince Béla, later Béla III, was betrothed to Manuel I’s daughter Maria and received the title of despot. He was treated as a prospective heir, but the engagement was dissolved after Manuel’s son Alexios was born in 1169. Béla subsequently returned to Hungary and became king.

Trade also formed part of frontier diplomacy. Agreements with Italian maritime cities offered commercial privileges, reduced tariffs, special quarters and, in some cases, their own courts. These concessions could bring ships and revenue or secure naval assistance against a dangerous enemy, as when Alexios I Komnenos relied on relations with Italian powers during the Norman threat.

Manuel II travelled to western Europe from 1399 to 1403 to seek help against Ottoman pressure. He visited Paris and spent the winter of 1400–1401 with Henry IV in England. His personal negotiations placed the emperor before western rulers from whom he sought military and financial support.