The prelude to, and execution of, the Normandy landings.
D-Day: June 6, 1944, the day when Allied forces stormed the beaches of Normandy to retake France from the Germans. They hoped to take the Germans by surprise, and their decision to brave rough weather to make their landings certainly accomplished that, but despite these small advantages, the American forces at Utah and Omaha Beach had to overcome monumental challenges to establish a successful beachhead.
The Germans expected the Allies to invade France to re-open the Western Front, but they did not know when or where the invasion would start - thanks largely to the operations of MI5, British intelligence services, who staged an elaborate deception called Operation Bodyguard designed to make the Germans think they would be invading Pas de Calais instead of their real target: Normandy.
Although the French government surrendered to the German invasion, French people rose up and formed resistance groups to take their country back. Charles de Gaulle and his Free French took advantage of these independent movements to help organize actions that would greatly aid the Allied landings at Normandy.
The Germans had established a secure barrier against the Allied invasion of France - or so they believed, until the D-Day landings in Normandy caught them by surprise and the Atlantic Wall quickly fell apart.