The Byzantines were the inheritors of the Roman Empire. The Emperor Constantine founded a new capital on the site of the ancient city of Byzantium in AD 330, renaming it Constantinople. Strategically situated, the city stood at the crossroads of Europe and Asia, where commerce between the Black Sea and the Mediterranean could be regulated. By the year 395, the empire had been permanently divided into eastern and western halves, each ruled by a co-equal emperor. When the last emperor of Rome was deposed in 476, the 'Roman' Emperor in Constantinople continued the imperial tradition.

The Byzantine emperor established no permanent missions in foreign countries though he usually sent the same highly trusted nobles and clerics on his embassies. As a matter of practice, these ambassadors were familiar with the countries they visited, either through previous travels or thorough their ethnic backgrounds. Even so, they were thoroughly briefed before they set out. Not only were they drilled on the details of the goals to be achieved, but they were also apprised of current developments in the court they were visiting. Constant contact was maintained with Constantinople, and diplomatic missions could sometimes last up to a year. The Byzantines probably initiated the practice of sending regular diplomatic reports home to the government.

What separated Byzantium from other nations of the early Middle Ages was its active involvement in manipulating internal events in other countries. Today we take for granted the existence of government agencies which gather and interpret intelligence, cultivate support in foreign circles and perhaps even instigate rebellion. To find such a sophisticated and centralized arrangement as early as the sixth century is truly remarkable.

To aid in dealing with other nations, the Byzantines established an organization called the 'Bureau of Barbarians', which gathered information from every source imaginable (even priests) and kept files on who was influential, who was susceptible to bribery, what a nation's historical roots were, what was likely to impress them, etc. In many cases, the information gathered by the Bureau was the first written record of these peoples, since barbarian tribes rarely had writing of their own. Armed with this knowledge, Byzantine emperors and diplomats had a complete understanding of the strengths of their allies and the weaknesses of their enemies.

The Byzantines employed a number of tactics, both overt and covert, to achieve their aims through diplomatic means rather than through force of arms: the use of ceremony was one such tactic. Imagine yourself as the chief of a nomadic tribe whose home is the steppes of central Asia. You are visited by representatives of the Byzantine emperor who shower you with fabulous gifts and invite you to the imperial palace in Constantinople. Your entourage arrives in a city inhabited by almost half a million people - perhaps three times the size of your entire tribe. Its buildings are protected by huge walls, deep moats and well-armed soldiers. You see goods from all over the world in the bazaars. You view centuries-old cathedrals and are mystified by the Christian ritual.

You are led to a huge, ornate palace. On either side of you in the audience hall there are golden mechanical lions that open their mouths and roar. In golden trees are mechanical birds who sing. In front of you, seated upon a golden throne, is the emperor, attended by a chief minister. You approach the throne and prostrate yourself in front of it. You are bidden to rise and when you look up you discover that the emperor, throne and all, is suspended high above your head. Later, imperial officials give you rich presents and inform you that more wealth and support will be forthcoming if you will fight the emperor's enemies (pocketing any booty you may pick up along the way). It was a rare tribal chief who would turn down such an offer. This process was repeated time and time again throughout the history of Byzantium and it encouraged many to ally with the empire.

Another tactic was bribery. The bezant was the dollar of the Middle Ages and it purchased a lot of influence. Money was spread around freely, but bribery was actually very cost-effective. Often a well-placed bag of gold saved Byzantium from raising, supplying and deploying an army. No one was considered above targeting for bribery. In the late eleventh century, a Seljuk Sultan sent an ambassador to Constantinople to settle a border dispute. The Emperor Alexius I Comnenus struck a secret deal with the ambassador, 'buying' the fortress of Sinope from him. By the time the Sultan discovered what had happened; Byzantine troops had already occupied the city.

Some 200 years later, the empire's greatest enemy was Charles of Anjou, who controlled the island of Sicily and much of the Italian mainland. Charles had ambitions to take Constantinople and establish himself as emperor. Byzantine Emperor Michael VIII Palaeologus prevented an Angevin attack in 1270 by sending a shipment of gold to Pope Nicholas III. In exchange, the pope forbade Charles to attack Constantinople and diverted his efforts to a crusade in Tunisia.

A further diplomatic ploy was the use of surrogates. The Byzantines hated the expense of war and could hardly afford the cost in human life. Often they would get others to fight for them. If the Bulgars were troublesome, the Russians were called in. If the Russians were troublesome the Patzinaks (a central Asian tribe) were summoned. The Cumans and Uzes acted as checks on the Patzinaks and so on. The Byzantines almost always had an ally to the geographic rear of a potential enemy.

The Byzantine emperor maintained a 'stable' of pretenders to almost every foreign throne in the known world. For instance, if the Turkish sultan seemed poised to attack, the Byzantine emperor could release a pretender, perhaps a younger brother of the Sultan. With Byzantine gold in his pockets and some armed supporters, the pretender could be counted on to wreak havoc in Turkish territory, spoiling the Sultan's attack.

In 1282, faced once again by the threat posed by Charles of Anjou, Michael VIII helped instigate the War of the Sicilian Vespers, in which native Sicilians rose up against Angevin rule. The rebellion ended Charles' dream of ruling in Constantinople. Michael VIII himself wrote: 'should I dare to claim that I was God's instrument to bring freedom to the Sicilians, then I should only be stating the truth'.

The word 'byzantine' has come to mean 'devious or characterized by intrigue'. This is due to some of the plots of questionable morality (but indisputable utility) that Byzantine emperors concocted. The Byzantines were of the opinion that anything done in the name of the Sacred Empire could not be judged treachery. Though they were diligent in adhering to the letter of their international agreements, they often violated the spirit of them. Strategic advantage was sought with fervor in every situation.

The Emperor Heraclius once intercepted a message from the Persian King Chosroes which ordered the execution of one of his generals, Shahr-Baraz. Heraclius added the names of 400 other Persian officers to the list and diverted the message to Shahr-Baraz. Heraclius' stratagem was deviously brilliant. Had the executions been carried out, the Persian military would have been decapitated. Instead, Shahr-Baraz and the other officers rose in rebellion against Chosroes and overthrew him, subsequently making peace with Byzantium.

In another episode, a hostile Venetian fleet wintered at the island of Chios, directly threatening Byzantine territory. The Venetians sent ambassadors to Constantinople to negotiate an agreement. The Emperor Manuel I Comnenus refused to see them. The ambassadors returned to Chios with a Byzantine official, who suggested another embassy. The Venetian Doge commanding the fleet agreed to do so. After the second embassy had departed, illness swept through the Venetian camp. More than 1,000 soldiers and sailors died within a few days. The second embassy returned without having met with the emperor.

Sick from the plague (rumors spread that the Byzantines had poisoned the water), the Venetians sent a third embassy to Constantinople. By now well-informed of conditions in the Venetian camp, Manuel realized he need make no concessions. He stretched out negotiations for so long that the Doge was obliged to withdraw the fleet or face a mutiny among his ailing sailors. As the fleet limped back to Venice, a Byzantine naval force attacked without warning and decimated the Venetians. Soon afterward, Manuel sent a message to the Doge which literally added insult to injury: 'Your nation has for a long time behaved with great stupidity'.

It is important to resist the temptation to dismiss all these tactics as self-serving, self-justifying and Machiavellian. Had the Byzantines been less so, European history might have been greatly changed. Byzantine diplomacy was crucial not only in preserving the Byzantine Empire, but in preventing the Islamization of Europe. Without this outpost of Christendom deflecting the Muslim tide from the seventh century to the fifteenth, it is unlikely that Western civilization as we now know it would have endured. By the time the Ottoman Sultan Mehmet II took the city of Constantinople by assault in 1453 and renamed it Istanbul, the states of Eastern Europe had absorbed enough Byzantine culture (and diplomatic technique) to stand on their own. The walls of Constantinople and the imperial diplomats gave the fledgling Christian religion 700 years to grow and prosper.