In 1939, the Wehrmacht attacked France with a 1:1 ratio in manpower. It took 3 weeks to overrun it.
In 1944, the US and the UK landed with combined force in Normandy and advanced with a 3:1 manpower superiority, with a 5:1 superiority whenever they attacked. They had near complete air superiority. It took them 7 months to conquer France.
That’s Prussian military tradition in action.
I’m confident Germany could have won if Hitler just hadn’t messed up the battle plans so many times.
The Dunkerque evacuation was only possible since Hitler panicked and ordered the panzer divisions to halt. A proper surrounding with the following tank shock would have destroyed whatever the British could have used to defend against an invasion.
In the Battle of Britain, the Luftwaffe had almost destroyed the RAF and Britain was ripe for bombing or conquest, but suddenly a lone bomb raid over Berlin was regarded as a personal insult by Hitler, and he ordered the bombing of civilian London, giving the RAF time to recover.
During fall 1941, Hitler ordered his troops to, instead of conquering Moscow, go towards Ukraine and its abundant food stores. Hitler moaned about how his generals don’t understand war economics, while the effects of conquering Moscow would have outweighed Ukraine heavily. The entire railroad network of USSR would have been messed up with the fall of Moscow. The army would have got proper winter shelter. The soldiers’ spirits would certainly have risen, and the Russians would most certainly have felt a huge blow to their morale.
Hitler replaced several generals simply because they disagreed with him, which was very fatak for the armies’ front performance.
And, most peculiar of all must be the failure to deal with Operation Overlord. Only a few hours’ drive from the beaches, there was a Panzer army which probably could have thrown back at least a few beachheads into the sea. It was though under Hitler’s personal command. At the time of the landing, Hitler was sleeping, and nobody was allowed to wake him up regardless of anything. Consequence? When Hitler finally woke up, several hours had passed and the beachheads were too well fortified to be assaulted.