On the opposite side, Hitler Youth (Hitlerjugend) was an organization in Nazi Germany that trained youth physically and indoctrinated them with Nazi ideology to the point of fanaticism. By the end of World War II, members of the Hitler Youth were taken into the army at increasingly younger ages. During the Battle of Berlin in 1945 they were a major part of the German defenses.
Even the Soviet Union used boy soldiers during WW2
Some children found by Red Army soldiers without their parents in liberated areas, they were adopted, they lived with soldiers, got food, care and so on.
BOY SOLDIERS IN THE RUSSIAN ARMY DURING WW2