Whereas Victorian optimists imagined that armed conflict would gradually disappear as the world continued to head for universal peace and prosperity, the 20th century wiped out any such illusions. These reflections mark the centenary of WW1, whose true horrors gradually unfolded despite official attempts at censorship. "The pity of war" is first examined through the eyes of artists and poets, before turning to an overview of how thinking about the conduct and morality of war developed down the centuries. Are there still lessons to be learnt? - read on in the final chapter.