"Jesus asked his disciples, saying, Whom do men say that I the son of man am? And they said, Some say that thou art John the Baptist; some, Elias; and others Jeremias or one of the prophets. He saith unto them, But whom say ye that I am? And Simon Peter answered and said THOU ART THE CHRIST, THE SON OF THE LIVING GOD.
And Jesus answered and said unto him, Blessed art thou Simon Bar-jona, for flesh and blood hath not revealed it unto thee, but my Father which is in heaven. And I say also unto thee, that thou art Peter. And upon this rock I will build my church, and the gates of hell shall not prevail against it." Matt. 16:13-18.
Thus, Peter was hailed as the first among the disciples and the leader. He went to Rome, and where Peter was, there was the leadership of the Church.