I see my favourite historical fiction author has not been mentioned, which has to be remedied forthwith.
Steven Pressfield writes mainly of the ancient world (in terms of his historical fiction novels), but if that's not too outlandish for you I highly recommend him. His first book in the genre,
Gates of Fire, is particularly excellent in my opinion. It is basically the movie
300 stripped of the fantastic and bizarre, telling the story of the Battle of Thermopylae from the viewpoint of the participants and in a very realistic and believeable way.