Who is Captain John Murray from Sharpe's Rifles: Richard Sharpe and the French Invasion of Galicia, January 1809 and what is their importance?

Captain John Murray genuinely likes Richard Sharpe and tries to do what he can to help Sharpe become a more effective leader. He gives Sharpe advice and tells him that he should make an ally of Patrick Harper. He also bequeaths his sword to Sharpe upon his death, so that the other riflemen will know that he likes Sharpe.