"they come to know their desires as Wellington knew Napoleon, or as Sherlock Holmes knew Moriarty"

Lewis compares a Christian's battles with his desires to two other great conflicts--one historical, one literary.

Arthur Wellesley, the first Duke of Wellington, defeated Napoleon at the Battle of Waterloo on June 18, 1815. You can see a detailed history of the battle here.

Sherlock Holmes's arch-enemy was Professor Moriarty. He appears or is mentioned in "The Final Problem," The Valley of Fear, "The Empty House," and other Holmes stories. "In 1891 ... [Moriarty] pursued the detective across Europe to the [Reichenbach] Falls in Switzerland, where the two fought and Moriarty fell to his death" (internationalhero.co.uk).