Click on the link to the Oxford First World War Poetry unit on Sassoon and work your way through as many of the poems/letters as you wish.
http://www.oucs.ox.ac.uk/ww1lit/education/tutorials/intro/sassoon/counter.html
Explanatory Notes not covered in Oxford tutorials.
Lewis gun: A light machine gun, designed in 1911 by U.S. Army Col. Isaac Lewis, and widely used by British and Empire forces from 1915 onwards.
Sap: A covering over a trench; the extension of a trench from within the trench itself to a point beneath an enemy’s fortifications.
Allemands: Germans, from the French “Allemand,”; German: sometimes referred to as the “Alleyman.”
Five-nines: 5.9-calibre shells.
Fire-step: A board or ledge in a trench, upon which soldiers stand when firing.