I am probably, if not definitely wrong when I say iambic pentameters. Tetrameters is more accurate as each line of the first four consist of four feet, so sorry for the bum steer. I would assume that by the phrase "In dead men breath" the author is alluding to the hereafter, in other words despite the horrors they have suffered they will live on in another world. I am not an expert in English Lit. and am more than happy to be contradicted. It's just that I remember that WWI poems were a major topic when I was at school.