I'm a history buff and the first time I saw the movie, it was the result of having found quite possibly the only movie that had anything at all to do with the Franco-Prussian War of 1870-71. It was with good fortune that it was well-done, and I was surprised at really how good the movie was. In terms analogous to recent movies, this movie is more like Thin Red Line or Empire of the Sun than it is Saving Private Ryan or Enemy At The Gates. By this I mean that the movie's setting is historical, and precise, but the events and interactions of the characters transpire this and are more about the conflicts themselves... man vs. man.. man vs. himself.
The film begins just before the Franco-Prussian War, where rumors that Napoleon III has been diplomatically taunting the King of Prussia are spreading across the French countryside. Again.. this isn't the story per se, it is simply the exposition of the film. If you don't know much about the Franco-Prussian War, then this movie might spark some interest in you doing some internet research on it, but I'll hold back on going into a historical diatribe on the causations and the results. Just know that the result of these diplomatic blunders result, ultimately, in the Prussians calling Napoleon III's bluff, invading France, capturing Napoleon III almost immediately and then crowning their King Wilhelm as the Emperor of all Germany after they take Paris in 1871. The culmination of this war leads to the creation of the German Nation.
Now, the movie really is the story of a French peasant who has gone to war in place of a rich man (this happened often back then). He has left behind a girl he loves, a classic story. As the Prussians tear through the French lines and cities with terrible precision, the main character finds himself in a predicament where he must choose to die or desert his company. He chooses the latter, and the rest of the movie is his adventure of trying to get back to his home in Sauvignon (pronounced "SHO-veen-yon" for all you wine lovers), back to the girl he loves, and living with the fear of always being stalked, both by enemy and "friend". Along the way, he meets an ethnic-German orphan boy from the Alsace- Lorraine region (which the new nation of Germany annexed after 1871, and thus helped spark the fires of revenge in France that would be a factor in leading up to WWI almost 50 years later), who he protects and tries to take care of.
Although I've described the historical aspects of this movie mainly, it's only because these are the parts we can nail down for sure. History is written, and movies are made about them constantly. But the introspective nature of this film is more in line with movies about conflict and war that question the purpose of life, its meaning, what is the difference between people on opposing sides of a war, is there a difference really? etc. etc.
If you enjoyed movies such as A Midnight Clear, Europa Europa or Thin Red Line, you will probably not be disappointed (unless you only like WWII movies) in this film. It also reminds me of Bergman's Seventh Seal, with its "soul searching" that is analogous to the actual adventure that has befallen the characters. It is quiet, very silent and introspective, with an ending that could very well be more somber than any Bergman film.