The full title of this book is “Operation Barbarossa and Germany’s Defeat in the East”. This would not fit in the post title box.
The thesis of this book is that the German Invasion of Russia had already ‘failed’ by August 1941, at the battles at Smolensk. Despite the fact that grand encirclements at Kiev and during Typhoon still were in the future, the seeds of failure were already apparent at this early date.
One difficulty was a lack of means – the German Army was just too small. As they moved deeper into Russia, they could no longer support offensives on all three fronts, North, South, and Center. At this stage, Center was stripped to support North and South. In 1942 and later only one front could advance, and after that the retreat began.
Another difficulty was lack of support – the deep penetration required massive logistical support to get supplies to the front and replace lost equipment. This support was overpromised and underdelivered universally. In August the spearheads were severely weakened due to losses from fighting and just from use.
The final problem was lack of direction. The aims of the Germans changed from week to week, from a drive to Moscow, to a drive to Leningrad, to a drive to acquire resources in the Ukraine. Much of the time the Germans worked at cross purposes. And they utterly failed to correctly judge the capacity and will to resist of the USSR, and their own limited ability to overcome this resistance.
While the war was not over after just six weeks, I think the assertion that the glib assumption that the Germans would roll over Russia was exploded, and that a long war was assured.