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My absolute favorite history book about Germany is Jospeh Rovan: „Geschichte der Deutschen“. You'll get it only second hand.
Anything from Sebastian Haffner is worth reading. He wrote mainly about the time from the early 20th century until the end of WW2.
Which language? Only englisch? If not: The best book i have ever read about german history is Geschichte der Deutschen by Joseph Rovan (also available in french). No new editions sold anymore, but you can used ones by amazon and others like rebuy or momox: https://www.amazon.de/Die-Geschichte-Deutschen-ihren-Urspr%C3%BCngen/dp/3446180524/ref=tmm_hrd_swatch_0?_encoding=UTF8&qid=1550090211&sr=8-2