The First Hundred Thousand (Barnes & Noble Digital Library): Being the Unofficial Chronicle of a Unit of "K(1)"

This 1916 novel, based on the author's combat experiences, tells the story of Kitchener's volunteer army from its mustering in 1914 to its first great blooding in the 1915 Battle of Loos, where, at the cost of 20,000 British casualties, not one inch of ground was gained.  Hay's tone perfectly captures the strong character of the soldiers and commanders in times of great difficulty.