Sadism, cruelty, and brutality tend to be associated with coldness and lack of emotion. In thrillers and suspense films, we are familiar with the idea of the emotionless psychopath, the hitman, or the pitiless serial killer. The ingenuity of mechanisation and the legacy of the Industrial Resolution turned out to have a dark side when it came inevitably to be applied to the machinery of war. The terrible carnage of the First World War was partly possible because the generals were still thinking of warfare as it was at the time of Waterloo, where two armies meet each other on the field of battle, rather than a new situation where men could be mechanically mown down in their thousands.