Ever since working on my very first novel manuscript--a mystery with a historical component concerning World War II Wales--I've been particularly fascinated with novels set during that period. The Welsh Girl by Peter Ho Davies--nominated for the Man Booker prize--actually does take place in WWII Wales, so of course I had to give it a whirl. While not a YA book per se, two of the viewpoint characters are seventeen and eighteen years old, and I think it might appeal to older teens with an interest in historical fiction.
Three main characters: a British investigator trying to mask his background as a German Jew; Karsten, an eighteen-year-old German prisoner of war detained in a camp in North Wales; and Esther, a seventeen-year-old Welsh farm girl whose life changes both drastically and subtly in the aftermath of the war. The story itself is musing and pensive in tone--much of the drama takes place within the characters themselves. This is not a novel of battle action, but rather a nuanced portrayal of rural life at the end of the war.
Markus Zusak's The Book Thief is a crossover in the sense that it's a YA novel that I firmly believe an adult audience would benefit from reading--the depth of theme and characterization is as great (possibly greater) than any literary "adult" novel. Told from a unique point of view--that of Death itself--The Book Thief relates the story of Liesel Meminger, a girl from a poor German family who goes to live with a slightly less poor foster family in the outskirts of Munich during the Second World War.
Of course, she wasn't always a book thief; this story chronicles not only her subtle reasons for stealing (or rescuing) the occasional book, but also her unique relationships with her foster parents, her new friends, and the Jewish man who is living in hiding in their basement. This is a truly touching story of what could arguably be deemed "ordinary Germans" caught up in the horrific Nazi regime--a story of tragedy but also hope; of people struggling to do good despite everything. It's really an epic saga. Because death is the narrator, I felt a bit of distance from Liesel, the main character, and I wasn't too sure how I felt about that, but really, this one's not to be missed.