In the early 320s, the political relationship between the co-emperors of the Roman Empire, Constantine and Licinus, was falling apart.
Although he had been committed to a policy of religious toleration, Licinus had begun a limited persecution of Christians in 321 or 322, which became a pretext for war between himself and Constantine, a professing Christian.
It was a war in which Constantine triumphed. Having unified the empire under his sole rule, Constantine now turned his attention to the unification of the church that was threatened by the quarrel between Arius and his bishop, Alexander of Alexandria.
