We all know about the M1 Garand and the Thompson submachine gun, but troops in Normandy used much more. See these 12 forgotten guns of the D-Day landings.
I was watching a documentary on the attack on Pointe du Hoc and they showed a picture of Field Marshal Rommel's visit to Pointe du Hoc, with the Guns installed. Unknown to the Allies, were that most of these guns were then moved to the Maisy Battery several miles inland (at bit of deception by the Germans). There are several books on the part that the Maisy Battery took during D-Day and now even tours of it, as more of it is excavated (the Allies had it buried under several feet of soil). It's a very interesting and little known history of the D-Day invasion until recently.
Maisy Battery is now open to the public after being buried for over 60 years. You can walk through 2 miles of original German trenches and explore WWII bunkers.