27. An Earlier Operation Barbarossa Would Not Have Changed Things
If Operation if Barbarossa had been launched two months earlier, in April, 1941, instead of June, it would have been even less successful and ground to a halt earlier, after advancing a shorter distance. The Germans advanced as rapidly and plunged as deeply into the USSR during the summer of 1941 because the months-long dry weather perfectly suited their Blitzkrieg style of maneuver warfare.
They needed good weather to make the best of their breakthroughs, followed by aggressive exploitation via deep armored thrusts. They needed dry roads to enable them to rush supplies forward to maintain the advance and allow the infantry to rapidly follow and consolidate the gains. They would not have had such weather had they invaded in April.