During the rise of tensions in the Second World War, as the Allies began to gain more ground, the Germans built the Atlantic Wall in Normandy.
The Atlantic Wall was built to act as a coastal defence system against an anticipated Allied invasion of Nazi-occupied Europe from the UK.
Standing there nowadays, as they were 75 years ago, is the battery at Longues Sur Mer on the cliffs between Gold and Omaha beaches.
They were built with four naval 150mm marine guns made by the Skoda factory in occupied Czechoslovakia between 1942 and 1944.
They had a range of 12 miles and were protected in a 6ft thick reinforced concrete.
For D-Day to succeed, these batteries, as well as several others, had to be overcome.
For this reason, the Allies planned to destroy 10 of the most dangerous. Longues Sur Mer was one of them, according to Claire Merlier, from the local tourist office.
Ms Merlier said the most "important" bombings happened during "the last days of May and at the beginning of June" in 1944:
"About 600 tonnes of bombs fell down here."
Despite the tonnage, the batteries survived.
"Normandy, during May and June, was completely covered with clouds," Ms Merlier said.
"Most of the bombs fell down naturally on the side but just behind in the village of Longues Sur Mer."
The extensive bombing disrupted communication systems on the batteries, which meant the barrage was not accurate.
The Allied bombing both prior to and on D-Day had done enough to minimise the effectiveness of that part of the Atlantic Wall.
For other parts, different tactics were chosen.
At Merville Battery, which is eight miles from Sword Beach, the Allies sent in 600 paratroopers to capture the guns.
But navigation errors in the Dakota force bringing them led to near disaster.
Hans Combee, a Merville battery guide, said:
"Quite a lot of the paratroopers were dropped way beyond the drop zone."
This meant only 150 paratroopers with no heavy weapons made it to Merville.
Despite this, they still managed to capture the guns and held them for D-Day.
Mr Combee added:
"It would have been a massacre on the beach."
"The guns here could have shot two-thirds of the landing craft and it could have sent mortars over the soldiers landing there.
"It was crucial for the Allies that these batteries were silenced."
But the reduced force could not hold on to the ground and had to withdraw.
The Germans then resumed control and fought off a further British attack by the Royal Marines on 8 June.
Both actions are remembered every year by the town of Merville-Franceville-Plage.