D-Day and the Normandy Landings
The massive armada included over 7,000 ships and landing craft manned by over 195,000 naval personnel from eight Allied countries. The troops consisted mainly of Americans, Britons, and Canadians, but members of the free French and many other nations also participated.
The D-Day invasion opened up the long-awaited Second Front against Hitler. According to the D-Day Museum, over 425,000 Allied and German troops were killed, wounded or went missing during the invasion.
More in the new immersive D-Day exhibit from the National Archives in Google Cultural Institute.