The Atlantic Wall was an extensive system of coastal fortification

Coastal artillery

Coastal artillery is the branch of armed forces concerned with operating anti-ship artillery or fixed gun batteries in coastal fortifications....

s built by Nazi Germany

Nazi Germany

Nazi Germany , also known as the Third Reich , but officially called German Reich from 1933 to 1943 and Greater German Reich from 26 June 1943 onward, is the name commonly used to refer to the state of Germany from 1933 to 1945, when it was a totalitarian dictatorship ruled by...

 between 1942 and 1944 along the western coast of Europe

Western Europe

Western Europe is a loose term for the collection of countries in the western most region of the European continents, though this definition is context-dependent and carries cultural and political connotations. One definition describes Western Europe as a geographic entity—the region lying in the...

 as a defense

Defense (military)

Defense has several uses in the sphere of military application.Personal defense implies measures taken by individual soldiers in protecting themselves whether by use of protective materials such as armor, or field construction of trenches or a bunker, or by using weapons that prevent the enemy...

 against an anticipated Allied invasion of the mainland continent from Great Britain

Great Britain

Great Britain or Britain is an island situated to the northwest of Continental Europe. It is the ninth largest island in the world, and the largest European island, as well as the largest of the British Isles...

.
On March 23, 1942 Führer Directive Number 40 called for the official creation of the Atlantic Wall. After the St. Nazaire Raid

St. Nazaire Raid

The St Nazaire Raid or Operation Chariot was a successful British amphibious attack on the heavily defended Normandie dry dock at St Nazaire in German-occupied France during the Second World War. The operation was undertaken by the Royal Navy and British Commandos under the auspices of Combined...

, on April 13, 1942 Adolf Hitler

Adolf Hitler

Adolf Hitler was an Austrian-born German politician and the leader of the National Socialist German Workers Party , commonly referred to as the Nazi Party). He was Chancellor of Germany from 1933 to 1945, and head of state from 1934 to 1945...

 ordered naval and submarine bases to be heavily defended. Fortifications remained concentrated around ports until late in 1943 when defences were increased in other areas.

Organisation Todt

Organisation Todt

The Todt Organisation, was a Third Reich civil and military engineering group in Germany named after its founder, Fritz Todt, an engineer and senior Nazi figure...

, which had designed the Siegfried Line

Siegfried Line

The original Siegfried line was a line of defensive forts and tank defences built by Germany as a section of the Hindenburg Line 1916–1917 in northern France during World War I...

 (Westwall) along the Franco

France

The French Republic , The French Republic , The French Republic , (commonly known as France , is a unitary semi-presidential republic in Western Europe with several overseas territories and islands located on other continents and in the Indian, Pacific, and Atlantic oceans. Metropolitan France...

-German border, was the chief engineering group responsible for the design and construction of the wall's major fortifications.