The dispute over Arianism had become a serious problem, which threatened to damage the peace and unity of the church and of the empire. Constantine, now sole claimant to the throne after the execution of Licinius, wrote a letter "to Athanasius and Arius". Constantine wrote the letter from Nicomedia, so some have concluded that Eusebius of Nicomedia, the bishop of Nicomedia and a supporter of Arius, may have been involved in the composition of the letter. The letter was given to Hosius of Córdoba, a respected older bishop, to deliver to the disputants in Alexandria. In the letter, Constantine requested that Alexander and Arius end their dispute.