# What is a bastion?
**A bastion is a pentagonal (arrow-shaped) projecting fortification that forms part of a defensive wall or rampart.** Developed in the 16th century, it is the key element of the trace italienne system of fortification that dominated European military architecture for three centuries.
## How it works
The bastion projects forward from the rampart, allowing defenders to fire along the curtain wall (the section of wall between two bastions) from the flanks. This eliminates dead angles where attackers could find shelter — a technique known as **flanking fire**.
## Components
– **Two faces** — the forward-facing sides forming the point
– **Two flanks** — the sides connecting to the main rampart
– **Gorge (throat)** — the open rear side connecting to the rampart
– **Salient** — the foremost point of the bastion
– **Curtain** — the wall section between two bastions
## Application
The Netherlands has dozens of fortified towns with bastions, such as Naarden, Bourtange, and Heusden. Many of these fortresses are preserved and listed as UNESCO World Heritage Sites. The bastion system was also widely adopted across Europe and colonial territories.
## Related terms
– Bastei
– Parapet
– Buttress
– Fortification
– Casemate
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