The ceremonies along Normandy's Channel coast reunited hundreds of veterans of the 1944 landings, the biggest sea-borne invasion in history.
French president also praised role of African troops whose sacrifice 'bound our country to Africa with a bond of blood that no one can undo'.
A total of 28 nations took part in Operation Dragoon on the beaches near Marseille on August 15, 1944, with a total force of 450,000 men.
French president urges people to fight current threats to peace with 'same vision, the same courage' as those who took part in Normandy landings.
President Hollande will pay tribute to the terrible civilian casualties suffered by the French due to Allied bombing during liberation of France.
UK monarch joins French president François Hollande in laying floral tribute at the tomb of the Unknown Soldier beneath the Arc de Triomphe.
Around 400 separate events will be held as American, Russian and British heads of state are among those marking 70th anniversary of landings.
French president says he will raise issue with US president who is flying in for talks in Paris ahead of Friday's D-Day commemorations.
Row over sale of warships to Russia and US fine for French bank have cooled relations ahead of presidential meeting on Normandy beach.
Soldier Jean-Louis Cremieux-Brilhac wrote up the invasion instructions for the French people that were broadcast via the BBC.
The inhabitants of Merville, where British paras fell storming a key German gun battery, had long prepared for Prince's 70th anniversary visit.
The British monarch will attend commemorations marking the 70th anniversary of the D-Day landings in Normandy in north-west France.
François Hollande travelled to the British military cemetery at Ranville to honour soldiers who died during the June 6th 1944 D-Day Normandy landings.