trying to figure out a movie

I am trying to remember a movie i watched when i was a kid. All I can remember of it, is that it was a war movie, either ww1 or ww2. One of the main characters in the movie was a runner, that ran all along the trenches bringing messeges. I remember the end with the runner, having to leave the trench, dropping his gun and just running towards the other side. The person on the other side, has a machine gun and esentially mows the guy down and that is basically how the movie ended.

if anyone knows of which movie I am talking about, it would be greatly appriciated.

Thanks
Kos