The answer:
It represented the beginning of the end of the war in Europe.
Explanation:
With the united forces of The Allies (France, The United States, Great Britain, Canada, the Soviet Union, and to an extent China) together they were able to make the Axis powers (Germany, Italy, and Japan) bleed at the highest of their power, during the battle of D-day. Because of The Axis loss on the war front, The Allies saw this as a turning point in the war, that the war would end and that they could win against The Axis powers.