Unanimous Declaration of the Council concerning Faith, and the Celebration of Easter
The result was that they were not only united as concerning the faith, but that the time for the celebration of the salutary feast of Easter was agreed on by all. Those points also which were sanctioned by the resolution of the whole body were committed to writing, and received the signature of each several member. Then the emperor, believing that he had thus obtained a second victory over the adversary of the Church, proceeded to solemnize a triumphal festival in honor of God.
Source: Life of Constantine (New Advent)