I highly recommend “The Rise and Fall of the Third Reich” by William Shrier. Like Par says he can be biased, but I cant think of an author that is not. In the forward of his book he even admits that there is a degree to bias to it since he lived many of the events. However he does for the most part report factually and does point out in his text when his opinion is involved. If you read objectively you will get a lot out of this book. I also recommend the “Berlin Diary” by the same author.
I appreciate the feedback. I’ll check out the Berlin Diary as well.