Sharpe's Fortress: The Siege of Gawilghur, December 1803 (The Sharpe Series, Book 3) by Bernard Cornwell
Ensign Richard Sharpe, newly made an officer, wishes he had stayed a sergeant after he is put in terrible danger by Sergeant Obadiah Hakeswill at the impregnable Gawilghur's ravine.
To regain his confidence and his authority, Sharpe will fight as he has never fought before.
Soldier, hero, rogue - Sharpe is the man you always want on your side. Born in poverty, he joined the army to escape jail and climbed the ranks by sheer brutal courage. He knows no other family than the regiment of the 95th Rifles whose green jacket he proudly wears.