shield-wall

Noun

shield wall (plural shield walls)

1. (historical) A defensive formation, used from antiquity through the early Middle Ages, in which soldiers stand shoulder to shoulder with their shields overlapping, creating a continuous barrier against enemy attack.
2. (otherwise archaic) A barrier.
3. (figuratively) An impenetrable barrier.
   • Still, in spite of the sensation of being caught between a ‘shield-wall’ of opaque references and a ‘word-hoard’ that is old and strange, such readers are also bound to feel a certain ‘shock of the new’.1999, Seamus Heaney, “Introduction”, in Beowulf, London: Faber and Faber, page xii