Free at Audible for the holiday season:
Christmas Eve, 1914
In 1914, the war which was to have been wrapped up by Christmas had - in reality - only just begun, as all sides entrenched themselves deeper into the Great War. Christmas Eve, 1914 follows one company of British officers as they rotate forward to spend their Christmas on the front lines, a mere 80 yards from the German guns. Upper- and working-class men and boys are thrown together into one trench and struggle to survive.
The link (hoping there's no affiliate tag in it):
http://www.audible.com/pd/Fiction/Ch...GBAP12151490UA