How did the Byzantine emperor become the spiritual leader of most eastern Christians?

Explanation:

In 330 A.D., Roman Emperor Constantine I chose Byzantium as the site of a “New Rome” with an eponymous capital city, Constantinople. Five years earlier, at the Council of Nicaea, Constantine had established Christianity — once an obscure Jewish sect — as Rome's official religion.

c. troops marched forward in close formation against newer, more accurate weapons

judaism, christianity and islam, are all abrahamic religions and therefore have in common the hebrew idea of a single god which is the source of all morality. the idea of the covenant is only related to judaism, while dharma is a concept of indian religions and the four noble truths are basic principles of buddhism.