The Normandy landings were the operations of the Allied Forces' invasion of Normandy on June 6th 1944. This remains to this day the largest seaborne invasion in history, and contributed hugely to the Allies' victory in the Second World War.
Planning for the invasion started well in advance and in the months leading up to the invasion itself, the Allies conducted a series of deceptions to mislead The Germans, who were expecting an invasion at some point. The phases of the moon, the tides and times of day were some of the many considerations the planners had to study and keep secret from the enemy.
D-Day in numbers:
The Allies landed 156,000 troops in Normandy on D-Day.
The armada consisted of 5,000 ships and landing craft and 50,000 vehicles, supported by 11,590 aircraft.
The Allied casualty figures for D-Day have been estimated at 10,000, including 2,500 dead. They include 6,603 Americans, 2,700 Brits and 946 Canadians.
German casualties are estimated at between 4,000 and 9,000 from the 30,000 men who were defending the Normandy beaches.
By June 11th, with the beachheads secured, more than 326,000 troops had crossed with more than 100,000 tons of military equipment.
The cache can be found at N54 58.579911A57923D579711A W001 37.577517A524618D580215D

You can validate your puzzle solution with certitude.