He said, "We live in a world of competing beliefs and claims about what is true, in such a world, it is rare for a struggle to emerge that speaks to something universal about humanity. The Second World War did that."
The Colleville cemetery, overlooks the Omaha Beach landing where US forces on June 6, 1944, suffered their greatest casualties in the assault against heavily fortified German defences.
Obama said, "It was unknowable then, but so much of the progress that would define the twentieth century, on both sides of the Atlantic, came down to the battle for a slice of beach only six miles long and two miles wide."
French president Nicolas Sarkozy, British prime minister Gordon Brown and Canadian prime minister Stephen Harper joined Obama in this ceremony.