A defense line or fortification line is a geographically recognizable line of troops and armament, fortified and set up to protect a high-value location or defend territory.
A defense line may be based on natural difficult terrain features, such as rivers or marshes, mountain ranges, or coastlines; temporary field fortification works such as trenches; and/or more permanent fortifications such as fortresses and bunkers.
List of defense lines
Some notable defense lines include:
Historical
Great Wall of China, China
Sassanian defense lines
Great Wall of Gorgan, Persia
Derbent Walls
Defense lines of the Netherlands
Median Wall (before 401 BC)
Limes Germanicus, Germany
Hadrian's Wall, United Kingdom (122)
Antonine Wall, United Kingdom (142)
Offa's Dyke, Wales (early 5th century)
The Pale, Ireland (late 12th century)
Serpent's Wall, Ukraine
The Zasechnaya cherta (Russian: Засечная черта)) on the southern and eastern borders of the Tsardom of Russia
Western Russian fortresses, Russia
Civil War Defenses of Washington, United States
Victoria Lines, Malta (1875)
Hindenburg Line, France (1916)
Maginot Line, France (1929)
Schuster Line, Luxembourg
Metaxas Line, Greece (1936-1941)
Mannerheim Line, Finland (1939–1940)
K-W Line, Belgium (1939)
Siegfried Line, Germany
Gothic Line, Italy
Winter Line (Gustav, Bernhardt and Hitler Lines), Italy (1943-1944)