My Boy Jack (2008) on Netflix

English gentleman author Rudyard Kipling, famous for the Jungle Book, uses his considerable influence, being on a War Office propaganda think tank, to get his nearly 18 year-old son John 'Jack', admitted for military service during World war I after he is repeatedly refused on account of his bad eyesight. He is enrolled in the Irish Guards: their patriotic dream but mother and sister's nightmare. After a short officer training course Jack gets command of a platoon and embarks in France. Soon, and just after his 18th birthday, his unit suffers terrible losses and Jack is reported missing. Now mother Caroline 'Carry' Kipling proves unstoppable pushing Rudyard's influence and half of England to help find out the truth. When it finally comes, there is far less glory than gore and guilt.