The rise of the Roman bishop.
This is another step taken in the centralization of the government of the Church.
Among the five patriarchs, the two most prominent were those of Rome and Constantinople, the two principal cities of the world. Several causes worked to raise the Roman bishop to the highest place. The chief was that he was bishop of the ancient capital of the world. For centuries authority had gone forth from Rome. Inevitably its bishop had a power that no other bishop could have. Another was the custom which grew up of appealing to the Roman bishop in church disputes. This custom became more influential through the encouragement from emperors.
Then from the fifth century, the so-called Petrine claim was generally accepted.
This is the claim that Christ made Peter first among the apostles and that Peter was the first bishop of Rome and bequeathed his primacy to his successors there so that they had a divine right to first place among the bishops.
The general acceptance of this made conditions just the same as though it were true. Besides all this, the Roman bishops pursued a consistent policy of holding all authority that they had gained, claiming still more, and taking advantage of every opportunity to use their power. A striking example of this was Leo I (440-461) sometimes called the "first pope" He asserted his universal authority in the strongest terms and claimed the right to give commands to bishops everywhere. Though his claims were utterly denied by the bishop of Constantinople, and met some resistance in the West, his aggressiveness greatly increased the power of his office.
As history says, the so-called Petrine claim was generally accepted.
Um, @Arch Stanton & @donadams ? Were you both aware of this?
History says, that it was not until the late second or early third century that Catholic tradition came to regard Peter as the first bishop of Rome, it was Linus, not Peter who was considered in the earliest succession lists to be the first pope.
You see, tradition is not a fact factory, it can't make something a historical fact when it is not. The nonsense of a pope wasn't even accepted until the fifth century.