I'm in the middle of a game as Germany. I broke through the French defenses and I now occupy all of France. I began to move my armor units to the east for my planned invasion of Poland and Russia, but had to stop for a moment and remove a small allied landing from across the channel. You'll get a kick out of this...France landed a single armored division on my shores. The interesting part is...they could have landed the division on about a dozen coastal provinces and been entirely unopposed. Instead, they chose to land in a province that I had a ton of infantry in. So much for the attempted invasion. The armor division lasted about 12 hours before its organization dropped to zero and it surrendered. Not much of a D-day invasion, huh?
I'm surprised there isn't a D-day event hardcoded into the game. Something where you could choose "yes" to the event and get a 6 month period in which your infantry could be produced twice as fast and basic amphibious warfare is easier to research.