The Enemy: A Book About Peace by Davide Cali and Serge Bloch

While this picture book is not for young children, I think it should be a must read for children in grades 5 and up.  Even adults will be touched by this story about a soldier, who is in a hole, shooting at the enemy every day, wanting to kill the enemy before the enemy kills him.  He knows the enemy is not a human being because his manual told him that.  However, one day he sneaks out and winds up in the enemy's hole and finds photographs of the enemy's family and the enemy's manual, which is just like his, except in that manual, the enemy has his face.  The story and illustrations are simple, but the message is powerful.  I highly recommend this book.