Fortifications

Fortifications are works built to defend a place or region from assault and to regulate access to terrain. They include permanent structures such as city walls, forts, and coastal batteries, as well as temporary or mobile works created during a campaign, siege, or battlefield. Fortifications reflect the balance between offense and defense, aiming to slow, deter, or channel attacking forces.

Early fortifications relied on natural terrain and simple walls. In ancient civilizations, enclosures were surrounded by earthen works and stone ramparts. During the medieval period, castles combined strong walls, towers, keeps, and moats with controlled gates. The introduction of gunpowder in the post-medieval era produced new forms of defense, notably the trace italienne or star fort, whose angular bastions and low, thick walls reduced artillery blind spots and improved fire coverage.

Common elements include walls or ramparts, towers for observation and fire, gates with defensive works, moats or ditches, and drawbridges. Advanced fortifications employ merlons and crenellations on parapets, and projecting structures such as bastions, ravelins, and glacis to absorb or deflect cannon fire and to provide fields of fire. Field fortifications used in campaigns include trenches, redoubts, and entrenchments laid out to impede movement and protect troops.

In the modern era, fortifications have retained strategic value in some contexts but are often used for defense planning, border control, or as cultural and historical sites. Many prominent fortifications survive as monuments, castles, or forts and are studied for military engineering, architecture, and national heritage.