The 16 Carmelite martyrs of Compiègne were guillotined during the French Revolution.
You can read more about them in the Catholic Encyclopedia.
Also recommended are:
The Song at the Scaffold by Gertrud Von Le Fort (Neumann Press) - approriate for high school or adult
To Quell the Terror: The Mystery of the Vocation of the Sixteen Carmelites of Compiegne Guillotined July 17, 1794 by William Bush (not yet reviewed for age-appropriateness)