This book by Geoffrey P. Megargee, published in 2000, is an eye-opener.
I read it in Dec 2002, having bought it at Times bookstore, Centrepoint Singapore (one of my favourite bookstores), during a visit to Singapore with my relatives.
It explains how the German High Command and Hitler ran the war. The research is excellent. The story that unfolds is riveting.
The Guns at Last Light, by Rick Atkinson, 2013, is the magnificent conclusion to Atkinson’s Liberation Trilogy.
I first read it in 2013. No writer has managed to better this trilogy, although in my view his 2nd volume, The Day of Battle, on the liberation of Italy, can be skipped if you neither have the time nor the resources to buy and read it.
The first volume, An Army at Dawn, is on the invasion of North Africa by the rookie American army, then led also by a rookie General Eisenhower.
In my view, this invasion was not strictly necessary. Still, it gave American soldiers and generals like Eisenhower and Bradley much-needed experience in planning, fighting, and winning the Normandy invasion.
The invasion was also to relieve pressure on the Russians fighting desperately on the Eastern Front.
P.S. Another invasion that was not necessary at all was the invasion of Manila by MacArthur. Purely to satisfy his big ego, it caused thousands of needless deaths of civilians and soldiers on both sides.