an open field fortification with two faces at an angle of 60°-120° to each other, protruding in the direction of the enemy. Small redans with blunt angles are called flèches.

In the 18th and 19th centuries, redans were built not only as separate fortifications, but also as continuous fortifications by connecting a series of redans with straight segments. Trenches with redan-type outlines were common in the fortified positions of most armies during World War I.