This man had a vision of a cross in the sky on which was written, "In this sign you will conquer," before that battle at Milvian Bridge.
A decree that this leader co-promulgated with Licinius granted toleration in his lands. He besieged the city of Marseille and may have forced its commander to commit suicide. That commander, Maximian, had a son who also fought against this man in a battle wherein that son, (*) Maxentius, died by drowning. This man had a vision of a cross in the sky on which was written, "In this sign you will conquer," before that battle at Milvian Bridge. For 10 points, name this fourth century Roman emperor who was the first Christian emperor.
A decree that this leader co-promulgated with Licinius granted toleration in his lands.
{Constantine I} [or {Constantine} the {Great}; or {Flavius Valerius Aurelius Constantinus}; prompt