Too Young the Hero

The true story of Calvin Graham who at the age of twelve, but looking quite a lot older, succeeded in joining the navy during World War II. In spite of his young age, he received a purple hart for his bravery in the battle of Guadalcanal. When he reported back to his unit after a leave, his world collapsed. Due to a misunderstanding he is reported as a deserter which is the start of a real nightmare (imdb)