The Last Kingdom (The Saxon Chronicles Series #1) by Bernard Cornwell
The Last Kingdom is the first of 13 books in the series. I recommend every one of them. Cornwell is a great writer, a great researcher, and has a better appreciation of what motivates men in battle and the psychology of leadership than 70% of our serving military officers. These are novels about the wars to unite England in the 800s and 900s. (There is also a TV series I haven’t seen yet.)The central character, Uhtred, is fictional, but there must have been several like him for the Saxons to prevail. If you like historical fiction and realistic battle scenes, you can’t beat these. In fact, all of Cornwell’s books are worth reading, and there are many.