My first thought on seeing the subject of WW1 trench warfare was to drop a link to the Hardcore History WW1 podcasts. They are excellent at getting across the sheer horror and enormity of WW1, something that was lost on me growing up in the US (we tend to focus on WW2). I suspect European listeners will be surprised by less, but for any American who doesn't know what I'm talking about if I mention Verdun or the Somme, I _highly_ recommend the podcasts. They are ~12 hours (so far) and riveting.