Try to watch the film "Oh what a lovely war" directed by Richard Attenborough. Have to say it is probably my favorite film.
This film gives a pretty good overview of the first world war, with a mixture of satire, jokes, songs, and some thought provoking moments.
He does start the film with an overview of how each of the various countries made friends with each other and offered to support each other.
It shows how the war affected the "Smith" family, a mythical family who represent the typical british man (from working clas to posh toff).
He sets the first world war on Brighton pier, making it seem as though it was all light hearted, but then flashes to scenes of the "real" war in France.
You never actually see anyone killed in the film, every time there is a gun shot, or an explosion, the camera just cuts to a single poppy, or a group of poppies.
And if the end does not bring a lump to your throat I will be very surprised.
It is available on DVD.
http://www.imdb.com/title/tt0064754/