The opening sequence in Saving Private Ryan is fantastic, but I find it less impressive than the battle scenes in Waterloo. That film pulled out all the stops to make everything look absolutely perfect (with the understandable exception of the cannons), and they manage to do so without much camera trickery. The hills match the original battle because they were excavated, there are thousands of soldiers in a shot because they filmed thousands of soldiers, and the cavalry charges were so realistic that the extras being filmed broke and ran. Regardless of what we can see in modern war films, it's basically impossible to reproduce that kind of feeling because nobody is willing to go to such lengths.