Good read. Richard Overy is a Brit, who has previously written and published ten books on WWII subjects, so he knows something about it. He picks six campaigns that he calls the war winners, as opposed to plenty of campaigns which simply consumed lives and resources without ever doing anything to win the war. I find Overy's views quite reasonable.
Overy starts out explaining how touch and go Allied victory was. In 1939,1940,and 1941 the Axis swept all before it. Their armies fought better and beat the Allied armies every time. Hitler overran all of Western Europe save Britain. Had the Germans been able to get the mines and farms and factories of this humongous area organized and producing, and the young men to enlist in the German army, he would have had an empire to match his enemies.
Overy's first crucial campaign was in the North Atlantic, where the U-boats had to be defeated. D-Day would not have been possible if the U-boats sank half the troops before they reached England. He attributes this victory to a handful of Consolidated B24 Liberator four engine bombers that had the range to run air patrols clean across the Atlantic. Prior to the Liberators, the shorter range patrol planes flying from Britain and Canada left a 1000 mile gap, "the black pit" seamen called it, where the U-boats ranged freely and sank thousands of merchantmen. Too get the Liberators onto the North Atlantic patrol took direct orders from Churchill. The RAF wanted to use them for bombing Germany and resisted putting them on a navy mission.
Overy's second key campaign is the bombing campaign against German industry. Right after the war, we ran some surveys concluding that strategic bombing had not been very effective. Overy disagrees, he cites the decline in German oil production, and the destruction of the German Air Force by the Allied long range fighters escorting the bombers. By the end of the war, the Germans didn't have enough gasoline to fill a Zippo lighter. As an old Air Force veteran, I agree with Overy on this one.
For a third key campaign, Overy chooses the eastern front. In 1941, the German Army completely out classed the Red Army and beat them every time. The Germans got to the outskirts of Moscow, had they been able to take the city, Russian resistance might well have collapsed. Somehow, the Russians stayed the course, rebuilt their armies, produced thousands of T-34 tanks, better than anything the Germans had, and inflicted the crushing defeat at Stalingrad in 1942. Before Stalingrad the Germans had beaten the Russians every time. After Stalingrad, the Russians beat the Germans every time.
The last key campaign was D-Day, where the Allies put a huge army ashore, in the teeth of German resistance and succeeded. The Allies then encircled and destroyed the German army in France. For the rest of the war, the German's fought with newly raised formations, or units pulled away from the eastern front.
Anyhow, if you are a WWII buff, you want to read this book.