I approach the game with the mindset that it's basically a petri dish for organically growing war stories. The fun comes from presenting the players with a scenario and just seeing what happens. If the DM happens to understand storytelling, he can certainly use that to his advantage, but story structure should never be a higher priority than player choice.

James Cameron said "You make the movie twice. Once during filming, and once during editing". You play the game to see what happens, and if you're really lucky, "what happens" might result in a story worth retelling.