On 20 May 324 at Nicaea (İznik, Turkey) the Council of Nicaea started. This meeting of bishops ended on 19 July 325. The Greek historian Socrates Scholasticus wrote about these events. The "Chronicle" of the Latin theologian Jerome and the "Chronicon Paschale" both say that on 25 July 325, it was Constantine's twentieth anniversary festival as emperor (his ) at Nicomedia (İzmit, Turkey).