sunken profile

The term "sunken profile" in the context of fortifications refers to a defensive design that emerged after the widespread adoption of gunpowder artillery. This design involved dropping fortress walls into the ground behind a ditch and protecting them with gradually sloping earthen ramparts. The forward face of these ramparts, known as the glacis, was sloped to allow defenders to sweep the area with cannon and harquebus fire from the parapet behind the ditch.1

This design aimed to protect the main fortress wall (the scarp) from artillery fire by using the glacis as a buffer. The counterscarp, the wall on the forward side of the ditch, was also faced with brick or stone. A level, sunken space behind the glacis, called the covered way, allowed defenders to gather for sorties under cover and out of sight of attackers. This, along with firing embrasures in the parapet wall, formed the fundamental elements of the new fortress profile. These principles remained largely consistent until the mid-19th century when rifled artillery changed warfare.1