Why did Germany manage to capture Denmark, Norway, Holland, Belgium, France relatively quickly?

At the beginning of World War II, the Germans were very strong militarily. They had well-trained troops, they had excellent and experienced commanders, and most importantly, they used the advanced tactics of war, which was based on the use of motorized units, especially takn. Thus, they practically swept away the enemy troops and defeated them to smithereens. In a matter of months, several European states surrendered, including France.