Answer:
It is considered a turning point because it forced Germany to fight on too many fronts, which led to their defeat. Germany did not have enough forces to defeat the Anglo American forces on the west, while in the same time they had to fight Soviets on the east.
Step-by-step explanation:
Invasion of Normandy was planned by the Allies after the meetings between the leaders of Britain, United States and Soviet Union. It was necessary to open a new front that will spread the German army. This eventually led to collapse of German army. Allies defeated Germany on all fronts, and Normandy became a synonym for victory.