Legeōn (λεγεών) is a Greek transliteration of the Latin legio, a Roman military unit of approximately 6,000 soldiers. In the NT it appears in the terrifying encounter of Mark 5:9 / Luke 8:30, where the demon-possessed man declares his name to Jesus as "Legion, for we are many\” — thousands of unclean spirits inhabiting one human person.
The name "Legion" carries multiple registers of meaning: (1) Military occupation — Roman legions occupied Israel; Legion of demons occupied a human soul. The demonic is portrayed with the same comprehensive, oppressive dominance as Roman imperial power. (2) Incomprehensible plurality — "we are many" speaks to the crushing, fragmenting nature of deep spiritual bondage. (3) Desperate acknowledgment of Jesus' authority — even a Legion bows and begs before the Son of God.
The liberation of the Gerasene demoniac is the most dramatic exorcism in the Gospels — a showcase of Jesus' absolute authority over every demonic force, no matter how numerous or deeply entrenched. The demons' request to enter the pigs, and their subsequent destruction, is a vivid parable: demonic forces ultimately destroy what they inhabit. Christ alone sets free what Legion has bound.