Who is Admiral Nelson from Sharpe's Trafalgar: Richard Sharpe and the Battle of Trafalgar, October 21, 1805 and what is their importance?

Admiral Nelson is the eader of the British Navy. He is described as a small man, who Sharpe observes is almost fragile. Sharpe, however, is so impressed that after sharing one meal with the man, admits that he would readily follow him into any battle situation. Nelson is commander of the Victory.