Wilfred Owen died before the end of the First World War, but the poetry he wrote carries a very strong message about the destructive nature of war. You will find some information on the poet and his writing at the following sites:
http://www.wilfredowen.org.uk/home
http://www.oucs.ox.ac.uk/ww1lit/collections/owen
You can find out more about the First World War here:
http://www.bbc.co.uk/history/worldwars/wwone/
