Enemy At The Gates: by William Craig.

Based on facts of battle for Stalingrad, fierce all the more due to its name, where the devastation wrought upon the poor and poorly equipped soldiers of the Russian army by the well prepared military engine was neatly foiled by the expertise of snipers, in particular one, trained by generations of people who live in desolate outer realms of eastern parts of Russia and hunt for life with literally life or death stakes what with wolves hunting solo or in packs and munition as precious as humans scarce.

The tide of the battle and the war turned partly due to the valour and steady fight given by such men and women - women fought alongside men in Russian army, albeit perhaps not in equal proportion just then - and their fierce intention to not give in to the stronger enemy.