The Etangs de L'Ermitage may or may not have been in existence at the time of the 1049-1051 campaign. For the purpose of the book, though, they represent an ideal half-way point between Alençon and Domfront, where William might base troops around a plentiful supply of fresh water.

These lakes, which I have chosen to call the Hermit's Lakes, are secluded in what is, even to this day, very dense woodland. Discovering them on a map and then searching for them on site was no easy feat. When I finally stumbled upon them, I was determined to use them, given how wonderful they were in terms of imagery, which mist lingering on the water.