For anyone who is interested in WWI trench-warfare, the book Ghosts Have Warm Hands, by Will R. Bird, is one I can't recommend strongly enough. Bird was a Canadian soldier who went over in 1916 and was there till the end; his account of what he went through is absolutely harrowing ... A propos some of these posts, Bird witnessed some grisly instances of acts of revenge on the part of Belgian civilians against German soldiers who didn't manage to get out quickly enough at the end ...

Another powerful book covering similar ground is the novel Generals Die in Bed, by Charles Yale Harrison, an American who at the age of 16 or 17 enlisted in the Canadian army ca 1914 and went overseas. It is a fairly short book, if time is a factor!