Salome and the Apparition of the Baptist's Head (1876) by Gustave Moreau - Public Domain Catholic Painting

According to the Synoptic Gospels, Herod, who was tetrarch, or sub-king, of Galilee under the Roman Empire, had imprisoned John the Baptist because he reproved Herod for divorcing his wife (Phasaelis, daughter of King Aretas of Nabataea) and unlawfully taking Herodias, the wife of his brother Herod Philip I. On Herod's birthday, Herodias' daughter (whom Josephus identifies as Salome) danced before the king and his guests. Her dancing pleased Herod so much that in his drunkenness he promised to give her anything she desired, up to half of his kingdom. When Salome asked her mother what she should request, she was told to ask for the head of John the Baptist on a platter. Although Herod was appalled by the request, he reluctantly agreed and had John executed in the prison.

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