The Atlantic Wall was an extensive system of coastal defense fortifications built by Nazi Germany from 1942 to 1944 against an anticipated Allied invasion of Nazi-occupied Europe from the United Kingdom during World War II. The wall was massive, running along the European coast from Denmark to the Spanish border. Gun emplacements were constructed at likely landing sites, beaches were mined and covered in barbed wire, obstacles were placed in strategic places to block landing craft, and 15 further Wehrmacht divisions were sent to defend the wall. 1,000,000 French workers were drafted to build the wall, and Adolf Hitler claimed that he had built the best fortification in history.
The German commander-in-chief in the West, Gerd von Rundstedt, did not have the numbers to defend the entire length, so he decided to deploy a large reserve of panzers northwest of Paris to react to any invasion; however, the commander of German troops in the Netherlands, Erwin Rommel - concerned about Allied air power - ordered that the panzers be sent to the most likely landing sites. Hitler decided to give Rundstedt a small force to be held as reserve, while the rest of the additional troops were scattered along the entire Atlantic seaboard in accordance with Rommel's wishes. There were neither enough reserves nor enough tanks near the coast, allowing for the Allies to breach the wall during Operation Overlord in June 1944. Most of the defenses were stormed within hours, and the wall would be partially demolished over the years, while most of it remained intact as historical ruins.