I know from doing some research for geneology, one of the things I did find out, is that gases were used to kill, by the germans. First a chlorene I believe used by the french, and then the germans liked the idea of the gases, and then there was phosgene, and then mustard, and now all gases are supposedly banned. This probably doesnt totally answer your question. But Time life has those dvd's you can buy. One is about The different battles on World War I.