A redoubt (historically redout) 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 meant to protect soldiers outside the main defensive line and can be a permanent structure or a hastily constructed temporary fortification. The word means "a place of retreat". Redoubts were a component of the military strategies of most European empires during the colonial era, especially in the outer works of Vauban-style fortresses made popular during the 17th century, although the concept of redoubts has existed since medieval times. A redoubt differs from a redan in that the redan is open in the rear, whereas the redoubt was considered an enclosed work. During the English Civil War, redoubts were frequently built to protect older fortifications from the more effective artillery of the period. Often close to ancient fortifications, there were small hills that overlooked the defences, but in previous centuries, they had been too far from the fortifications to be a threat. A small hill close to Worcester was used as an artillery platform by the Parliamentarians when they successfully besieged Worcester in 1646. In 1651 before the Battle of Worcester the hill was turned into a redoubt by the Royalists, (the remains of which can be seen today in Fort Royal Hill Park). During the battle, the Parliamentarians captured the redoubt and turned its guns on Worcester. In so doing they made the defence of the city untenable. That action effectively ended the battle, the last of the English Civil War. From 1715 onwards, the Order of Saint John built a number of redoubts in Malta, as part of an effort to improve the coastal fortifications of the islands. They were built in the middle of bays to prevent enemy forces from disembarking and outflanking the coastal batteries. The design of the redoubts was influenced by ones built in the French colonies. In all, eleven pentagonal redoubts and a few semi-circular or rectangular ones were built.