Born in London to a poor mother, Sharpe spent most of his youth in the inner city of London. When he killed someone, he went away to Yorkshire. He then joined a British line battalion, a regiment in the British Army. He was sent to India, where he saved the Duke of Wellington's life. For this, he was given a field commission to the rank of Lieutenant. He was then transferred to a Highland regiment, where he was not wanted, and was transferred into the 95th Rifles at Shorncliffe back in England. The 95th Rifles was then sent to northern Spain with General Moore's army. It was in Spain that he became friends with Patrick Harper.