Huw Edwards introduces live coverage of the centenary Somme commemoration at the Thiepval Memorial, France, to remember the one million casualties sustained on both sides during the 141 days of the battle. One hundred years on from the first day of this defining World War One battle, TRH The Prince of Wales and Duchess of Cornwall, TRH The Duke and Duchess of Cambridge and HRH Prince Henry of Wales will join heads of state and 10,000 spectators. The Thiepval Memorial stands in commemoration to the missing of the Somme, the 72,000 men that have no known grave.