Zwinger

Area between main and secondary walls of a fortification

A Zwinger is an open kill zone area between two defensive walls that is used for defensive purposes. Zwingers were built in the post-classical and early modern periods to improve the defence of castles and town walls. The term is usually left untranslated, but is sometimes rendered as "outer courtyard", presumably referring to the subsequent role of a Zwinger as a castle's defences became redundant and it was converted into a palace or schloss; however, this belies its original purpose as a form of killing ground for the defence. The word is linked with zwingen, "to force", perhaps because the Zwinger forced an enemy to negotiate it before assaulting the main defensive line. Essenwein states that the "main purpose of this feature was so that the besieging force could not reach the actual castle wall very easily with battering rams or belfries, but had to stop at the lower, outer wall; also that two ranks of archers, behind and above one another, could fire upon the approaching enemy".

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