A horse and his young owner are separated by war. An exceptionally poignant story of one horse's experience in the First World War. In , Joey, a young farm horse, is sold to the army and thrust into the midst. War Horse book summary & chapter summaries of War Horse novel. Michael Morpurgo's children's book ' War Horse ' tells the story of World War I through the eyes of Joey, a courageous young horse purchased by the Army. Main characters in War Horse book, analysis of key characters.