Redan is a feature of fortifications. It is a work in a V-shaped salient angle towards an expected attack. It can be made from earthworks or other material.
Saint Anthony's Battery in Qala, Malta, with a redan containing the entrance
"Cascalho" Redan in the city walls of Elvas, Portugal
A redoubt is a fort or fort system usually consisting of an enclosed defensive emplacement outside a larger fort, usually relying on earthworks, although some are constructed of stone or brick. It is
Redan
…angle with a vertex toward the enemy is called a flèche (arrow in French). The Bagration flèches were three redans backwards in echelon. The Shevardino Redoubt (another redan) was erected as an early warning post a mile in front of the Bagration flèches. A Redan hole or Redan is an aspect of golf course…
Vendôme Tower in Marsaxlokk. It is the only surviving tour-reduit in Malta.
The earth settles following the explosion of the mine beneath Hawthorn Ridge Redoubt on July 1, 1916