Battlements were placed o­n top of curtain walls allowing troops to walk along them to attack the enemy and defend the walls...

Submitted by Aubergine

Battlements made all the difference when it came to defending against castle walls being scaled because they allowed troops o­n top of the wall to retaliate by pushing away ladders, dropping stones and pouring boiling oil, etc.

There are three key aspects to battlements as shown below:

The walkway, also known as "allure", "wall walk" and "castle walk", allowed troops to move along the top of the wall:

Later castle designs extended the walkway out to the side of the top of the castle wall making a ledge and these were known as "parapets".

The raised "merlons" (pronounced "merluns") were usually made from stone and were between 3 and 6 feet high and usually between 3 and 5 feet wide. Some merlons would have arrow slits built in to them allowing archers to fire arrows with a greatly reduced risk of being hit themselves:

The "crenels", also known as "embrasures", were the gaps between merlons. They would usually be between 1 and 3 feet wide. By leaning over the crenels archers could fire arrows down the side of the castle wall and troops could push stones or tip oil over the edge of the wall.

To give extra protection, the crenels would sometimes be fitted with wooden flaps, roofs or shutters that could be opened or closed as required to give the desired mix of defence and attack options.

Although these battlements were a key feature of castles they still had limitations because they didn't allow troops to attack the land at the base of the castle wall, usually referred to as the berm, without risking attacks by enemy attackers.

Decorative Battlements

Because the battlements are such a distinctive feature of most castles, many normal buildings were given fake battlements to make them look more important and castle-like.

San Marino: Crenellated walls of Republic of San Marino

Some historians believe that the crenellated walls (merlons and crenels) may have been inspired by designs like Bamana urban architecture such as this domestic compund in Ségou-Koro: