Ravelin

The ravelin outside the Land Gate at Tilbury Fort

The Moers fortifications, designed by Simon Stevin, where ravelins appear as triangular shapes surrounded by water, with wall (shown in green) facing outwards with no wall on the inner side.

In 16th century Revelin Fortress became the strongest city fortress within Walls of Dubrovnik in Croatia.

A ravelin is a triangular fortification or detached outwork, located in front of the innerworks of a fortress (the curtain walls and bastions). Originally called a demi-lune, after the lunette, the ravelin is placed outside a castle and opposite a fortification curtain.

The edges of the ravelin are placed so that the guns there can sweep fire upon the attacking troops as they approach the curtain. The wall facing the inner fortifications is low and designed so that it will not provide shelter to attacking forces in case the ravelin is overtaken by the attackers or abandoned by the defenders.

The word appears in the Major-General's Song from the comic opera The Pirates of Penzance, by Gilbert & Sullivan, in which General Stanley sings, "In fact, when I know what is meant by mamelon and ravelin..."

See also

• List of established military terms
• Raveleijn (Efteling)