Although it lasted for over a thousand years, the Byzantine Empire is perceived as remote and eccentric, fascinating in itself but without much contemporary relevance. Michael Antonucci's 1993 article, War by Other Means: The Legacy of Byzantium, took a different approach, declaring that in the field of diplomacy Byzantium had something to teach the modern world. He focused on the way that the Byzantines compensated for their military weakness by resorting to covert diplomatic manoeuvrings.
A prime example occurred in the late 13th century, when the king of Sicily, Charles of Anjou, gathered a huge army and fleet to seize Constantinople. Unable to match such force, the Byzantine emperor, Michael VIII, made contact with Charles' restive Sicilian subjects, supplying them with money and arms, and sent envoys and a consignment of gold to the king of Aragon, whom he knew to have a grudge against Charles. The gamble paid off. An uprising in Palermo in the spring of 1282 – the Sicilian Vespers – was followed by an Aragonese invasion of Sicily. The threat to Constantinople evaporated overnight as Charles fought to defend his kingdom from the unexpected assault. Antonucci paralleled such diplomatic sleights of hand with events of the 1980s and early 1990s: US backing of the Kurds against Saddam Hussein and Soviet encouragement of nuclear disarmament groups in western Europe. They were all examples, he claimed, of diplomacy as a tool in the struggle between national interests, a continuation of war by other means.
Refreshing though Antonucci's thesis is, it is not always convincing. To start with, the examples that he used to illustrate Byzantine diplomacy were not always accurate. He claimed that in 1270 Michael VIII sent a gift of money to Pope Nicholas III, who in return told Charles to attack Muslim Tunisia rather than Christian Constantinople. In fact, Nicholas did not become pope until 1277. Second, in his enthusiasm for Byzantine diplomatic finesse, Antonucci envisaged an unlikely level of organisation and sophistication. There was certainly a kind of foreign ministry in Constantinople, the Bureau of Barbarians. On the other hand, there is no evidence that it was a kind of MI6 which 'kept files on who was influential and who was susceptible to bribery'.
Perhaps the greatest weakness in Antonucci's article was his insistence that Byzantine diplomacy prefigures modern realpolitik and the theories of Clausewitz and Machiavelli, where the practical takes precedence over the moral or ideological. In fact, diplomacy has often had an ideological underpinning that goes beyond national interests, whether the spread of a religion, the establishment of representative democracy and the free market, or the advance of the inevitable revolution and the workers' state. In the case of the Byzantines, that ideological basis was the conviction that their empire was no mere nation state among many. It was the Roman Empire, established by God at the time of the birth of Christ. It was as much part of the right order of things on earth as the Church and the Sacraments. To defend it went beyond simple patriotism: it was a sacred duty, which justified underhand practice. As a result, Byzantine diplomacy sought to achieve not only security or economic and territorial advantage but to vindicate ideological tenets. Treaties with other Christian powers almost always included a clause acknowledging the theoretical supremacy of the Byzantine emperor, even in cases where the treaty concluded a war that the Byzantines had lost. When they did win, they often demanded the defeated leader's participation in a public ceremony, where he had to grovel in the dust at the emperor's feet. Antonucci described how potential allies were invited to Constantinople to be overawed by the sight of the city's towering churches and palaces, but this was not just a cynical ploy. It reflected Byzantine beliefs about the place of the empire in the world; their diplomacy was designed to advance the will of God. Thus, while Antonucci highlighted an intriguing parallel with modern international relations, he neglected the differences that separate us from the vanished world of Byzantium.
Jonathan Harris is the author of The Lost World of Byzantium (Yale, 2015).