At the outset of the Second World War Canadians wanted to avoid the horrors encountered on the western front in 1914-18, one of the most significant of which was "shell shock." Most medical personnel preferred not to assign to combat those who showed neurotic symptoms during training, but this approach was challenged by the Canadian Psychological Association and by the new Personnel Selection Directorate established in 1941. Personnel Selection claimed to be able to distinguish, before training, between those suited and those unsuited to combat duty. However, when Canadian troops went into...