Today is Veterans Day (US) or Armistice Day. "Happy" seems an odd word to tack on to either one, but it's an important day to remember.
So to all the veterans I know--and don't know--thank you. This includes my father, my great uncle, my husband and father-in-law, my good friend Nathan, my ex-husband and his father...and many, many more.
There are many books about war, in all centuries, non-fiction and fiction. If you are interested in a slightly biased account that is an excellent first-hand depiction, I recommend The Ladies From Hell, by R. Douglas Pinkerton.
He was a Scot who penned a fairly short, terse memoir that includes enough of the horrors of trench warfare to give an idea of what these men--mostly very young men--went through.
At present, there are several modern mystery authors who write of the post WWI period, including Jacqueline Winspear, who writes the Maisie Dobbs series.
An excellent post WWI (Great War) mystery of the Golden Age of mystery is Dorothy L. Sayers's The Unpleasantness at the Bellona Club. Her own husband, Mac, was a veteran who suffered from mustard gas damage and shell shock.
So, again: thank you everyone, for serving your country.