Concurrent with the Council of Seleucia, four hundred bishops of the Western Roman Empire attend a church council called by the emperor and held at Ariminum (modern Rimini, Italy).

Most of the bishops in attendance are orthodox and accept the faith of Nicaea, but the Arian minority includes skilled diplomats who successfully undo the orthodox decision of the majority when it reaches the emperor.

The orthodox bishops remaining at Ariminum are then forced to recant and subscribe to an Arian creed drawn up at Nice in Thracia.

Pope Liberius, soon repudiating this creed, declares the Council of Ariminum without authority.