I loved reading historical novels when I was in middle school.
Definitely check out Dove and Sword by Nancy Garden. It's a novel about Joan of Arc, and PW says it's for 12+, but I think kids a little younger than that would still like it (I know I did!).
If you're looking for books for boys, check out Clara Bourreau's On the Run. That's a better bet for the younger set, but I think 5th grade would be fine. It's about a boy who goes, well, on the run, with his bank robber father. It's not only set in France, but it's actually translated from an original French novel. Unlike Dove and Sword, I haven't read it personally, but it got great reviews.
I haven't read these myself but have heard them recommended by others, thus I can't attest to grade-worthiness. The first is a light-hearted story about a quest that leads to humorous mishaps. The second is the story of a Scottish woman who gets caught up in the sorrows of World War II through her love for an RAF pilot. It gives a compelling look at the social history of WWII. The third is a mysterious story about a town, a girl and a woman, chocolate and Lent. Lives are contrasted, conflicted, meshed and intertwined before the end of the story. The last two have had movies made from their texts.
Chasing Cézanne, by Peter Mayle
Charlotte Gray, by Sebastian Faulks
Chocolat, by Joanne Harris
Here's a really good, timely one-- The Invention of Hugo Cabret by Brian Selznik. It is a longer novel, but has huge appeal for the middle school level. The protagonist, Hugo, actually lives (and hides) in a Paris train station. Students seem genuinely to enjoy Hugo's character, and the novel is incredibly imaginative and a fun read.