But he only did this when he thought the emperor was right! When one of the emperors came to visit his castle he was quite willing to give him a lecture on how an emperor should act.

Both the barbarians, with their hard-riding horsemen, and the valiant border lords played an important part in defending the Byzantine Empire from its enemies, but the Byzantines never really trusted either group. A barbarian chieftain was far too likely to ride off with his hordes and found a kingdom of his own as Theodoric had done in Italy. A border lord from Asia Minor was too likely to try to become emperor himself. Indeed, more than one had.

The Byzantines also had a navy, one of the best navies of the Middle Ages. But often they did not rely on it as they did on their army. For one thing, the emperors were always afraid of the navy for the same reason that they were afraid of the border lords of Asia. They were fearful that some admiral would use it to take their throne from them. Three admirals did just that. Another reason was that the Byzantines liked to be sure of what they were doing. But in those days, ships were flimsy and the seas were full of unknown rocks and sudden storms. The best of plans might be upset by the violence of nature, and so it was more dependable to fight on land.

Just the same, when the Byzantines had to, they were always able to get together a fleet, and it was usually a good one. When Justinian sent an invasion army to North Africa, he had enough ships to need 20,000 sailors. It was the navy that twice drove the Arabs from Constantinople. In 853 A.D., the Byzantines were able to send 300 ships against Egypt. A little later, Zoe Black Eyes could order a veritable armada all the way to Italy to drive Saracen sea raiders from their stronghold near Naples. When the Byzantines attacked the pirates in Crete, they were able to send 105 dromonds and 75 Pamphylians. The dromond was the battleship of the Middle Ages. It sometimes carried 300 men and was a bireme, that is, it had two decks of oars on each side, one under the other. A Pamphylian was a lighter, swifter cruiser. The admiral’s flagship was usually a Pamphylian. There were also galleys; they had only one bank of oars but were the swiftest of all.

It was the Byzantine navy that developed and used what was probably the first “secret weapon” of all history. This was the famous Greek fire. Even today nobody knows exactly what it was, except that it was a complicated mixture of chemicals, one of which may have been a crude form of petroleum.

The Byzantines pumped it at the enemy through huge tubes or hurled it at them from portable siphons almost like modern flame throwers. Even water would not put it out. So it was fairly easy to destroy an enemy fleet. Greek fire frightened the enemy even more.

But the Byzantines did not rely only on the army or the navy to win their battles for them. Helping them in every way was the Byzantine diplomatic service. For just as the Byzantines did not ever fight a battle if they could find some other way of winning it, so too they didn’t even begin a war unless they had to. Why fight if they could persuade an enemy to become their friend and ally? Why fight, and risk their own safety, if they could talk someone else into fighting for them? To the Byzantines, this made sense.

It was up to their diplomatic service to do this, and the reason it was able to do so very often was because here too the Byzantines knew just what they were doing. Under the Logothete of the Dromos, they had an almost modern intelligence system taken care of by a special department whose one job was to collect information about foreign nations.

How can such and such a country help the Byzantines and how can it hurt them?

How can it best be won over by the Byzantines—by force, by honors and favors, or by gifts?