One of the older movies that successully combines action with historical accuracy is The Devil's Brigade. At first I thought it was pure Hollywood, then I saw a History Channel special on the 1stSSF and realised they got it pretty much how it was in The Devil's Brigade.

Another older movie that is accurate and fun is teh one where Audie Murphy plays himself (title has hell in it, To Hell and Back or Hell is For Heroes or something)

The Longest Day is pretty accurate tries to portray not only the Americans but also the British, Germans, Free French, and the French Resistance. However some find this movie to be somewhat boring nowadays.
But like any John Wayne war film, it is really good.


Some good movies which aren't really accurate historically but you'll get a kick watching:

Kelly's Heroes,
Where Eagles Dare,
Force Ten From Navarone,
Dirty Dozen