There are two great books that tell the story from the standpoint of men in the trenches. The first is “Poilu” by Louis Barthas, who served in the French army from 1914 to 1918, spending most of his time as an enlisted man in front line units. The other is, “Goodbye to all That” by Robert Graves, who served as a junior officer in front line British units for much of the war. Both present a picture of unbridled, futile horror. Barthas’ book is currently available at Amazon; Graves’ is not. I highly recommend both.