I'm not a big fan of war books, but there are some boys who want to read nothing else. This 2001 title combines many good elements that make this a great read for your WWII obsessed boys.
Erik is only 16 when he is conscripted into the German army. He's not thrilled, because his grandparents are Russian. He gets sent to the front, and there is some rather graphic fighting. The sad conditions of war are all described-- the filth, the cold and damp, the battles that cause young boys to lose their lives. During one of these battles, Erik is badly injured and trapped under a tank with a dead Russian soldier-- he changes uniforms with him and emerges, pretending to be Russian but have amnesia. He ends up working in the hospital where he is treated, and escaping with one of the nurses when the fighting stops.
This was really fabulous for the idea that people are people, regardless of their country. At one point, Erik kills a German soldier who has opened fire on him in order to save his Russian companions. Things are not black and white during a war. The fighting in this book is not glorified.
I had a very dear friend who fought in the Wehrmacht. He didn't want to, but he had to. This gives some insight as to what he must have felt. This book is based on true stories of two people.