ravelijn

A ravelijn is a type of outlying fortification, typically consisting of a detached, open-topped earthen or masonry bastion, placed in front of a curtain wall or a main fortification. Its purpose was to provide an additional defensive position, protecting the main walls and gateways from direct assault and artillery fire. Ravelins were particularly common in the development of star forts and other Renaissance and early modern defensive systems.

These structures were designed to be isolated from the main fortress, often surrounded by a moat, and accessible only by a narrow bridge or causeway. This isolation allowed defenders in the ravelin to engage attacking forces at close range and to enfilade them as they attempted to breach the main walls. Their open-topped design meant they could not be easily defended from above once captured, but their strategic placement often made them a difficult obstacle for attackers to overcome.

The development of the ravelin reflected a shift in siege warfare, moving towards more sophisticated defenses capable of withstanding increasingly powerful artillery. They were integral to the concept of mutually supporting defensive works, where the destruction or capture of one element would not lead to the immediate fall of the entire fortification. Examples of ravelins can be found in many historical fortresses across Europe, contributing to their complex and layered defensive layouts.