A redoubt is a fort or fort system usually consisting of an enclosed defensive emplacement outside a larger fort. It is meant to protect soldiers outside the main line of defense and is often hastily constructed. Redoubts were a component of the military strategies of most European empires during the colonial era, although the concept of redoubts has existed back to medieval times. Fortifications (Latin fortis, strong, and facere, to make) are military constructions designed for defensive warfare. ...

By definition, a redoubt's walls always contain only obtuse (vice, acute) angles.

See the Lines of Torres Vedras, the Battle of Borodino and the Siege of Yorktown for examples where redoubts played a crucial role in military history. The Lines of Torres Vedras The Lines of Torres Vedras were a line of forts in Portugal built in secrecy between November 1809 and September 1810 during the Peninsular War. ... Combatants First French Empire Russian Empire Commanders Napoleon Bonaparte Mikhail Illarionovich Kutuzov Strength 130,000 600 cannon[1] 154,000 624 cannon[1] Casualties 35,000[1] 44,000[1] The Battle of Borodino (Russian: , French: ) (September 7, 1812, or August 26 in the Julian calendar then used in Russia... Combatants United States France Great Britain German mercenaries Commanders George Washington Comte de Rochambeau Lord Cornwallis Charles O’Hara Banastre Tarleton {Stationed at Gloucester, Virginia} Strength 10,800 French 8,845 Americans 7,500 Casualties 62 dead 190 wounded[2] 156 killed 326 wounded 7,018 captured[1] The Siege...

An good example of a preserved redoubt is the Eastbourne Redoubt Fortress Miltary Museum, Royal Parade, Eastbourne East Sussex, United Kingdom. Eastbourne Redoubt Fortress Military Museum Eastbourne Redoubt was built in Eastbourne, East Sussex, between 1804 and 1810 to support the associated Martello Towers. ...