Why did the Allies land on the beaches of Normandy on D-Day?

Correct answer: To take advantage of false information given to the Germans about an invasion elsewhere.

The Germans knew that the Allies were planning an advance into France to try to retake the Western front in World War II. The Allies used various forms of deception under "Operation Fortitude" to get the Germans to think they were getting ready to invade in the Pas-de-Calais region in northern France, keeping their actual plans to invade at the beaches of Normandy (in northwest France) a top secret. Troops landed at five sites along the Normandy beaches in the famous "D-Day" invasion of 1944.

The Allies held deception exercises that had the Germans convinced that the invasion would occur in the Pas-de-Calais, while the real target was Normandy (the actual beach names given to the operation were Utah and Omaha.) Even when the Germans saw the Allied fleet coming at Normandy, they were convinced that Normandy was the deception. If they responded to Normandy, then Pas-de-Calais would be defenseless.