REDANS, or Redans, in Fortification, a kind of indented work in form of the teeth of a saw, with salient and re-entering angles; to the end that one part may flank or defend another. It is likewise called saw-work and indented work. The lines or faces in this flank one another.

Redens are used in fortifying walls, where it is not necessary to be at the expense of building bastions; as when they stand on the side of a river running through a garrison town, a marsh, the sea, &c. But the fault of such fortification is, that the besiegers from one battery may ruin both the sides of the tenaille or front of a place, and make an assault without fear of being enfiladed, since the defences are mined. The parapet of the corridor is likewise often redented or carried on by the way of redens. The redens was used before bastions were invented, and some people think them preferable.