The Byzantines were able to keep Constantinople safe because they were one of the few peoples living in the time between the fall of Rome and modern days who had a strong government and one that worked. The rest of the Roman Empire had been divided by conquest into a good hundred or more independent units. These were ruled by kings, princes, dukes, marquises, and counts, and some cities were even free republics headed by wrangling priors. Their boundaries were always changing, and nobody ever knew just who was governing whom today, and who would be tomorrow. But the eastern half of the Roman Empire had a single government which was almost always orderly. The Byzantines were able to do it because they had a fine army, and when they needed it, a swift and deadly navy—to say nothing of a diplomatic corps with a well-paid staff of skillful, highly trained diplomats. They were able to do it because of their Christianity. After Antioch (in Syria) and Alexandria (in Egypt) had been captured by the Arabs, Constantinople was the most important Christian city except Rome. And as far as the Byzantines were concerned, the state worked for Christianity, and Christianity worked for the state. Finally, the Byzantine Empire was able to stand firm and to last so long because the Byzantines could afford to spend what they needed to. Their government was tremendously expensive. Their army and their navy with its _strategoi_ and _drungariuses_ (generals and admirals) cost them a lot of money and so did their extravagant ambassadors. The church with its own mighty army of high officials and lesser functionaries was very expensive too. But as long as the Byzantines were not only able to support emperor, army, navy, diplomats, and the church, but were _willing_ to do so, the Byzantine Empire flourished and was great. It was only after they began to economize, when a lot of Byzantines decided they were spending too much on the army, that their troubles began. At the head of the government was the emperor, and he was certainly the most absolute ruler there could possibly be. Even in the earliest days of the empire, he was chief of the Byzantine state, commander in chief of the army and navy, the only one who could make laws, and the head of the Byzantine courts. In other words, he was equivalent to the President, Congress, and the Supreme Court of the United States rolled into one. When he became _basileus_, he was even more than that. The Great King was master and owner as well as sovereign, and his subjects became slaves. They had to humble themselves on the ground before him, and foreigners had to as well. Beside that, he was the head of the Byzantine church (now known as the Greek, or Orthodox Eastern, Church), and in this connection took on another title, _isapostolos_, which is Greek for “equal to the Apostles.”