Which world war ii battle involved the greatest mobilization of land and sea forces?

The name of the battle is the Battle of Normandy.

This attack lead by the Allied powers in 1944 was considered a significant turning point in World War II. This allowed the Allied forces to gain a foothold in France, a country that had been controlled by the Axis powers for almost 2 years. This also allowed the Allied Powers to start their Western European campaign. This campaign was critical to the success of the Allied powers, as their ability to take control in France made this a two front war for the Germany military.