I read a novel over 35 years ago and I do not remember the title or author. It was about one of the Crusades and was very detailed and graphic
There have been a number of novels about the Crusades. Do you remember any of the characters featured? Alfred Duggan, for example, was a well-regarded author who wrote many historical novels about the Crusades, over 35 years ago; one of his books might be a possibility. Cecilia Holland and Zoe Oldenbourg are also possibilities--they both published novels about the Crusades in the 1970s.
Thanks for any additional clues!