Geoffrey of Monmouth claimed that this man was the grandson of King Cole through his mother Helena, and Lorenzo Valla proved that this man's supposed 
Geoffrey of Monmouth claimed that this man was the grandson of King Cole through his mother Helena, and Lorenzo Valla proved that this man's supposed grant to Pope Sylvester of the lands of Rome, this man's namesake donation, was a fraud. He ended the Tetrarchy at the battle of Milvean Bridge and issued the 313 AD edict of Milan. For 10 points, name this Roman Emperor, the first to convert to Christianity.
Geoffrey of Monmouth claimed that this man was the grandson of King Cole through his mother Helena, and Lorenzo Valla proved that this man's supposed grant to Pope Sylvester of the lands of Rome, this man's namesake donation, was a fraud.
Constantine the Great [or Constantine I; or Flavius Valerius Aurelius Constantinus]