I’m currently making my way through The Third Reich Trilogy as an audiobook and it is hands down the best researched, most in-depth piece of history I’ve ever read / listened to.
Evans must have spent half his life in primary sources and uses that research to great effect. The book includes many diary and newspaper extracts from the time for example (including liberal use of Goebbels diary) and goes into detail in all sorts of areas that paint a very clear picture of everyday life in Germany at the time.
It’s long (around 90 hours audio or over 2000 pages) but I have learned so much from it.
It’s not a perfect fit for the question, but I absolutely loved the Flashman books by George MacDonald Fraser.
Flashman was the antagonist in a much older book called Tom Brown School Days. Flashman was the school bully who made Tom’s life hell.
In the Flashman novels, he has been expelled from the private school and joins the military. As an officer in the British army, he is present at and influences most of the major battles of the early and middle 19th century.
He is an appalling coward, a disgusting misogynist, and generally all-round horrible person.
But the books do an excellent job of describing the politics and military actions, as well as the cultures where they are set. There may be better history books, but nothing has stayed in my mind as well as Fraser’s descriptions as the retreat from Afghanistan, Little Bighorn, The charge of the light brigade, and many others.