D-Day - Gun Batteries

In support of German defenders of the Atlantic Wall coastline, a number of reinforced concrete emplacements were built to house heavy artillery pieces. These were situated behind the beaches, where they could fire upon invading troops as well as ships.
 
In planning for the D-Day invasion, Allied photo-reconnaissance aircraft covered the coastal hinterlands of France, Belgium and the Netherlands and photographic interpreters carefully identified and recorded the position and state of construction of gun emplacements and their defences. In the weeks before D-Day, these batteries were subjected to heavy aerial bombardment by Allied aircraft.