The ceremonies along Normandy's Channel coast reunited hundreds of veterans of the 1944 landings, the biggest sea-borne invasion in history.
The inhabitants of Merville, where British paras fell storming a key German gun battery, had long prepared for Prince's 70th anniversary visit.
Bernard Kouchner said errors were made, but dismissed Rwandan accusations that France directly helped in the1994 genocide in the country.
Officials from about 30 countries are meeting in Paris to plan four years of commemorative events for the 100th anniversary of World War I.
France will set tone for the way the world marks the 1914-18 war; two of its bloodiest battles, at Verdun and the Somme, took place on French soil.