What is a ravelin?

A ravelin is a detached outwork of a fortress, usually triangular, placed in the ditch in front of the curtain, the stretch of rampart between two bastions. Its gorge, the rear face towards the fortress, is left open or only lightly walled.

What it does

1. Screens the curtain and the fortress gate from direct artillery fire.
2. Flanks the faces of the adjoining bastions, so that they can cover one another.
3. Splits the attack. The attacker has to divide his forces and is drawn into a crossfire in the process.
4. Denies cover once taken. Because the gorge is open, a captured ravelin offers the attacker no shelter from the main rampart.

The ravelin connects to the main rampart by a narrow bridge or an access causeway. In some works it sits as an island within its own additional ditch.

How it differs from a bastion and a hornwork

Work	Position	Form
Bastion	Permanent, integral part of the main rampart, projecting from it	Five sided, with two faces, two flanks and the gorge at the rampart
Ravelin	Stands free in front of it, in the ditch	Usually triangular, gorge left open
Hornwork	Pushed well forward to command ground beyond the ditch	Much larger, with two demi bastions and a connecting curtain at the front

History

The earliest documented ravelin is the one at Sarzanello in Italy, dated 1497. The work was originally called a demi-lune after its crescent form. During the 16th century engineers such as Daniel Specklin enlarged it considerably and made it a standard component of the bastion system.

In the Netherlands the ravelins of Bourtange survive, from the reconstruction to the state of 1742. At Goes two ravelins carry their own names: de Groene Jager and de Grenadier.

Terms in other languages

German uses Ravelin, with Wallschild as its own native name. Dutch uses ravelijn. French keeps demi-lune.

Related terms

• Bastion
• Curtain wall
• Hornwork
• Fortification
• Ditch
• Lunette

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