The Children of Freedom by Marc Levy

A French Jewish man looks back on the period in his life when he was 18 years old, working in the French Resistance in Toulouse during World War II. He and his younger brother, Claude, were part of the 35th brigade, which was a historical reality. The members of this brigade were almost all young people, aged 20 or less. They came from Poland, Italy, Hungary, Spain and other places. They risked their lives many times over to impede the Germans who had occupied France. Most of them died.

Adventure is coupled with tragedy. The storytelling is straight-forward and the chapters are brief. It's an adult novel that is suitable for teens in Grade 9 and up.