One of the bloodiest clashes of the First World War, the five-month battle of the Somme claimed the lives of more than 127,000 British soldiers, with more than 57,000 British casualties on the first day alone. How did the battle of the Somme start? And how did the battle of the Somme affect WW1? Here are eight facts about the battle of the Somme, one of Britain's most famous battles…