COLLEVILLE-SUR-MER , France ( CNN ) -- World leaders gave thanks Saturday to military veterans for their efforts in the D-Day landings of 65 years ago at a ceremony in northwest France , warning that their legacy must not be forgotten as the world faces renewed threats of tyranny . President Obama and Britain 's Prince Charles were among those attending the ceremony . President Obama joined Britain 's Prime Minister Gordon Brown , France 's President Nicolas Sarkozy and Canada 's Prime Minister Stephen Harper at a ceremony at the American Cemetary in Normandy , close where many died in the World War II offensive . More than 150,000 allied troops , about half of them Americans , took part in D-Day on June 6 , 1944 , overwhelming German forces in an operation that proved a turning point in driving the Nazis out of France . Allied forces secured the beaches at a cost of about 10,000 casualties in what was the first step in a campaign that would , in a matter of weeks , liberate Paris , which had been under Nazi occupation for more than four years . Brown praised those who fought on that day , saying , `` as long as freedom lives , their deeds will never die . '' He said their sacrifices had put obligations on people living today in what he called `` the great covenant of D-Day . `` We must be as if liberators for our day and our generation too , '' he said , citing Burma ( renamed Myanmar ) and Zimbabwe , as well as the `` mortal threat of poverty , hunger , illiteracy , disease and want . '' Obama addressed the 288 veterans said to be attending the ceremony , telling them : `` You are why we keep coming back . '' Watch Obama deliver speech to veterans » . `` You remind us that in the end , human destiny is not determined by forces beyond our control . You remind us that our future is not shaped by mere chance or circumstance . `` It has always been up to us , '' he said . Watch Obama arrive in France » . He urged the world to remember what happened at nearby Omaha Beach , one of the main landing points for U.S. troops involved in the operation . `` Friends and veterans , what we can not forget -- what we must not forget -- is that D-Day was a time and a place where the bravery and selflessness of a few was able to change the course of an entire century . '' Sarkozy described the horrors of the battle , where so many died before they were able to land that `` those who did make it ashore waded through the bodies of the dead and wounded that floated in on the tide . '' He cited a letter from a U.S. soldier who said the day `` was like a waking nightmare . The ground was so strewn with bodies that you could practically cross the beach without touching the sand . '' `` Never , never will France forget , '' he vowed . The speeches were followed by a 21-gun salute , a lone trumpter playing taps and a flyover by American , British and French jets . Among veterans attending Saturday 's remembrance ceremonies will be 86-year-old former British soldier Jim Tuckwell , who said the events will help those present to remember fallen comrades lost in the heat of battle . `` There was no time to mourn , you did n't have time to mourn , '' he said , recalling the events of 1944 . Read Tuckwell 's story . `` And the worst thing about later battles was that when you lost people , you normally had to bury them yourself . You could n't leave the bodies on the ground , there was nowhere else to put them . ''
Dignitaries , the World War II veterans pay tribute to D-Day fallen . President France , UK 's Sarkozy , UK 's Brown among those attending . More than 150,000 allied troops took part in operation on D-Day .