Just finished 'War in the West' by Brian Clarke. The basic premise of this alternative history is that Hitler falls ill and dies at the start of the war and is replaced by Reinhard Heydrich.
Heydrich being smarter and more rational simply doesn't make the mistakes Hitler made. Aided by some amazingly effective intelligence assets and no Ultra, he conducts an almost faultless campaign. The seizure of the Azores brings Britain to its knees and the book ends with the fall of the Soviet Union in a campaign season.
I have to say that I struggled with this book. Some parts of the conflict are dealt with in minute detail and others brushed over. I kept expecting some twist at the end when it would all go wrong for the infallible Heydrich. But it doesn't, and this is the silliest part of a very silly story. The author clearly hasn't heard of Von Moltke's maxim "No battle plan ever survived first contact with the enemy". If he had he would understand that things go wrong in war and other challenges would have caused the German's difficulties, even without Hitler's crazier interventions.
In summary this is very poor fantasy, not even alternative history. Not worth the effort or the very modest 79p it costs to download on the Kindle.