a Roman legion: the largest unit of the Roman army, roughly six thousand soldiers, used in the Gospels as an image of an overwhelming host.
Legion is not originally a Greek word at all. It is Latin, borrowed straight from the Roman army, where a legion was the largest fighting unit: somewhere between five and six thousand professional soldiers. By the first century the term was everywhere in the eastern Mediterranean, stamped on soldiers' papers and monuments, so anyone living under Rome knew exactly how large and how organized a legion was.
The Gospel writers reach for that scale on purpose. When a tormented man in gentile country tells Jesus that his name is "Legion, for we are many," the word turns the size of a whole army into a picture of how many spirits are holding him. The same weight works in reverse at Jesus' arrest: he says his Father could send him more than twelve legions of angels, something like seventy thousand, a force far beyond any earthly army and drawn from the heavenly host (צָבָא) that stands behind the title "LORD of hosts," which he chooses not to summon.
Because Rome's soldiers were the largest human power the ancient world knew, some readers also hear a political edge in the demons' name, especially in Mark. Scholars disagree over how loud that echo is (see the note on Mark 5:9). What every reading shares is the same sense of overwhelming, organized might, whether it belongs to the powers that torment a man or to the God who could rescue him.
Nuances
Whether "Legion" in the Gerasene exorcism (Mark 5:9) carries a deliberate anti-Roman political meaning, or names only the demonic multitude.
- majorityThe name is purely an image of demonic multitude: the man is held by a whole army of spirits, and "Legion" carries none of its Roman military-political overtones here.; William L. Lane, The Gospel According to Mark, NICNT (Eerdmans, 1974), 184-85; R. T. France, The Gospel of Mark, NIGTC (Eerdmans, 2002), 227-35
- contestedThe Roman resonance is real and may be activated by Mark, but the episode is not a one-to-one allegory of Rome; the political implication is at most secondary.; Adela Yarbro Collins, Mark, Hermeneia (Fortress, 2007), 269-70; Joel Marcus, Mark 1-8, Anchor Bible 27 (Doubleday, 2000), 351-52
- minorityThe exorcism is a coded expulsion of Roman imperial power: the demon named for Rome's army is drowned in the sea like Pharaoh's army, sometimes tied to the boar emblem of Legio X Fretensis.; Ched Myers, Binding the Strong Man (Orbis, 1988), 190-94; Warren Carter, 'Cross-Gendered Romans and Mark's Jesus,' JBL 134.1 (2015): 139-55