Who is Ensign Charles Nicholls from Sharpe's Christmas and what is their importance?

Seventeen-year-old, Ensign Charles Nicholls, is a recent army recruit. Colonel Hagan charges Nicholls with summoning Sharpe when his battalion is dispatched to Irati. Sharpe worries about Nicholls and orders d'Alembord to watch over him. The boy is later shot and killed by Colonel Caillou under a flag of truce.