I'm so glad you posted this. I've never seen the series but I've heard good things about it and I really enjoy Sean Bean.
I first saw some episodes 10+ years ago on PBS' "Masterpiece Theater".
I now own the first 14 episodes ("Challenge" is #15) on DVD.
You (and others not familiar with the series) may want to do a bit of Googling to familiarize yourself with the characters, etc.
Briefly:
In "Sharpe's Rifles" (the first episode), Richard Sharpe (Sean Bean) is a sargeant in General Arthur Wellesleys' (soon to be the Duke of Wellington) 95th Rifles. Sharpe saves the Generals life from French dragoons.
Out of gratitide, Wellesley makes Sharpe an officer, and gives him command of the "Chosen Men".
The "Chosen Men" are elite riflemen, selected for their exceptional skill and bravery. The "Chosen Men" wear a white arm band on their riflemans' green uniform, signifying courage.
The series, of course, follows the adventures of Richard Sharpe and his "Chosen Men".
Note: In previous episodes, Sir Henry Simmerson became an enemy of Sharpe. Simmerson detested Sharpe because of his low birth (being a commoner, raised from the ranks).
In a disastrous attack on French forces, Simmerson lost the Kings' colors. He attempted to blame the fiasco on Sharpe, but failed. This has added to the animosity between the two.
For those who haven't seen any of the "Sharpe's" series, I strongly suggest purchasing or renting the first four episodes (at least):
Sharpe's Rifles
Sharpe's Eagle
Sharpe's Comapny
Sharpe's Enemy
Note: Most of the Chosen Men died during the Napoleonic War, with the exception of Sgt. Patrick Harper (O'Mally).